Exercises in Physics 1000023899
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'1000
Exercises
in.
Physics.
BY
A. AUTHOU
OF
"ElXMBNTS
P.
GAGE,
OF
Ph.D.,
PHYSICS,"
SciBNOB," "Physical
"INTRODUCTION
Tbchnics/*
TO
PHTSIOAL
Etc.
BOSTON: PUBLISHED
BY
THE
AUTHOR.
1890.
byGoogk
Digitized
^oU^^^'T:i\ r.
?(3.
M-on
HARVARD COLLEGE Gl.
GINN
"
MARCH
r
UBRART
r.p
COMPANY 17, 1927
COPTBIOHT,
1890,
BY
A.
Typographt
bt
P.
GAGE.
J. S. GusHiNQ
" Co., Boston,
byGoogk
Digitized
PREFACE.
by suggestingthe him
by enabling He
whether
oral
copiesin
the hands been
noting
become
them
that the
to extend
catch
though
hopes
leniency; and, be
to
matter,
"
a
the
excused
the usual
that
information
on
from
ments. attain-
ment encourage-
all
questions,
authors.
By placing
them
expects these
branches
of
room, class-
ponder, and the
limits
Exercises
of to
his instruction.
into the field of
speculativescience,so
and
physics as
others; and
a
be, will,it is hoped, awaken
the
an
to
beyond
glimpse of the future
errors
his
laboratory and
have
pupil,
of
different
the
would
author
Maxwell, it
by
or
in
deeply into the mysteries of
more
author
The
teachers
he
as
their
pushed
Thomson,
things, hurried to peer
been
being
as
pupils after the
auxiliaryin
pupil may
by Rowland,
begs
questions
valuable
a
by
; to the
take
consistent,object
thoroughly discussed
such
Inquirieshave
with
of his
prescribed text-book,
their
be
to
written, whether
or
physics have
encouraging
must,
general
inexperienced teacher,
should
statement
the
to
self-examination
careful
a
interpretsthe last
cramming,
to
make
to
who
his instruction
which
turn
assistance
; to the
preparing for his daily work
in
teacher
is to render
Exercises
of these
aim
The
in the
ground
of
in him
being
these
a
desire
will be treated
a
much-employed teacher,
questions upon
penalty for preparing
of
nature.
following pages
answering
view
descried
a
the
subject-
book.
byGoogk
Digitized
byGoogk
Digitized
1000
EXERCISES
PHYSICS.
IN
INTRODUCTORY
What
is the
2.
What
is natural
3.
When
1.
can "
does
science ?
one's
of
knowledge
is
he
physicsf-
science and
speaking about,
begin
?
"
When
he
it in numbers."
express
Thomson, 4.
whom
To who
those 6. a
of the term
etymologicalmeaning
what
measure
EXERCISES.
the
name
and
of
do
How
measured, of two
we
endeavor
certain
6.
do
all the great advances
owe
to find how
we
measure
quantity of
called
unit, is contained
is
a
the
kind
same
parts ; viz.,a numerical
thing of
certain
the
in the
and
agreed
the
quantity
By
a
times
many
be
quantity to
to be
measured.
phrase consisting
denominational, the latter being
a
kind
same
magnitude
"
as
To
"
Maxwell,
anything."
physicalquantity expressed?
a
of the
is of
?
knowledge
quantity? By finding how
a
definite
How
a
there
much
in
the
as
upon
quantity to be expressed, men
among
as
a
standard
unit. 7.
What
is
8.
What
is
certain 9. 10.
which tumbler room,
11.
hypothesis? theory? It is
an a
effects that What
is
Which
a
of
bodies
to
are
to the
?
limited
body Any the followingterms of
two
of
cause
senses.
portion of are
matter.
applicableto substances,and
viz.,desk, rod, iron, wood,
matter;
water, lake,
chalk, glass,tumbler, air, the air in the
iceberg,ice,earth, the earth what
explanation of the hidden
an
evident
of water, crayon,
In
provisionalassumption of facts.
A
ways
may
?
physics be taught?
Inductivelyand
deductively. 12.
certain
What
is
a
natural
law?
physical quantities,or
effects of natural
phenomena
An
expression of the relation between
of the order follow
one
in
which
the
causes
and
another.
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2
EXERCISES
What
13.
is the kinetic
of properties What
14.
IN
PHYSICS.
theoryof
?
matter
It
that all the
assumes
merely attributes of motion. from the mutual phenomenon ? A changeresulting
matter
is a
are
action of bodies. What
15.
is
name
they are ? 16.
17.
related ; in other
reasoningby Which, discover
experiment, we
words, by which
natural
laws
covered dis-
are
Induction. tumbler
A
when
full of water
Quantityof
in
matter
is
capableof receivingmany ? Explain. Is water impenetrable a body is expressed brieflyby what
full of certain gases.
tumblers
of
process and observation
haying acquired facts by how
to the
given
word? gram of water occupieswhat space? The quantity of matter per unit of space is
18.
A
19.
expressed by what
?
word
FORCE. do you know that force exists ? is the physical of motion? cause
20.
How
21.
What
22.
Is
23.
What
24.
Is friction
of 25.
force
a
always doing something?
is the most
force ?
a
Physics, p. 162.] is meant What by
direction,e.g. toward its effect
force
universal force known
on
the
the
body
actingin the
[See DanielPs the statement
north ?
whether
same
Show
that force is but
27.
How
is force measured
an
28.
a
force acts in
from
a
pullingor
a
were
partialaspectof when
it does
followingstatement:
How
bringingthem does
appliedat either 31.
certain
a
in
pushing
stress.
a
produce motion?
not
example. Criticise the
30.
a
there be any difference
"The
tendency of
generallyto produce motion." 29. What preventsthe attractive force between
body
the Principles
on
direction ?
26.
Give
force
the
Text-Book
that
Would
?
in contact
the tension
end
of
with a
one
force is
the molecules
of
another ?
string compare
with
the
force
?
If the force at each
end
is not
the same,
a
what
will
happen ?
byGoogk
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3
GEAVITATION.
each
that the tension of
Show
32.
end is three,and not six,as
pulledwith string supposed by some.
a
a
force of three at
Explain how attraction between a drop of water and the end becomes at an of a finger, beinginsensible when at a sensible distance, insensible distance sufficientto supportthe drop. 33.
34.
So far
as
cohesion
is concerned, is it necessary to
existence of any other force than that of gravity,or any than the Newtonian? No ; so says Sir William Thomson.
assume
the
other law
stringsupportsa weightof 4 lbs. at its lower end, a weight of 6 lbs. above the first, and a weight of 5 lbs. above the second. Find the tensions of the three partsof the string. 36. What effect does an unbalanced force actingon a body always produce? 35. A
37. Let
an
unbalanced
force of 8 lbs. act for five minutes
on
each
bodies,one
of two
of 100 having a mass of 10 lbs.,the other a mass lbs. In which will it produce the greaterchange of momentum ? 38. You stand on the earth and hold an applein your hand. Show that as long as you hold the applethe gravitation stress between the either in apple and your hand can produce no change of momentum the appleor the earth. 39. Show that as soon to support the apple an equal as you cease will occur in both the apple and the earth. change of momentum 40. A gun weighing 20 tons is suspended by a cable so as to be free to swing like a pendulum. A shell weighing 10 lbs. is projected from the gun, and its maximum velocityis 800 yds. per second. What is the maximum of the gun's rebound ? velocity 41. A loaded block of wood weighing 100 lbs. is suspended so as to swing freely.A cannon-ball weighing 10 lbs. is thrown into the with a velocity of 10 ft. per second. wood, causing the block to move of the mechanical Suppose that none energy of the ball is wasted in of the ball? 1010 ft. per sec. heat,etc.,what was the velocity
GRAVITATION. Who
42.
between 43.
discovered that heaviness
is due
to action at
Sir Isaac Newton. portionsof matter? ? What is the best way of defining gravitation
a
distance
two
Let
a
stone
drop.
i
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4
EXERCISES
does the force of
44.
How
45.
between Distinguish
46. Under
though 47. of
what
its mass State
gravitydiffer
weightand
circumstances
remains
the
from
mass,
will the
weight of
phenomena which the
stress between gravitation
other forces ?
body
a
vary,
?
same
well-known
some
PHYSICS.
IN.
evidence positive
and the earth.*
sun
which
are
weight of a body depends. 49. Is there any truth in the legend that Newton led to the was of the laws of gravitation on seeingan apple fall from a tree discovery in his garden ? Nothing could be farther from the truth. 50. If a body weighs 8 lbs., does it follow that its mass is 8 lbs. ? form of dynamometer with which 51. Describe some you are and whether it is of capable measuring a push or a acquainted, state pull. between the sun and the earth at 52. The stress, called gravity, to what? different partsof the latter'sorbit is proportional in physics between 53. Show the importanceof distinguishing and weight. mass all
48.
State two
54.
On
what
If
the
the force of
conditions would
cubical vessel filledwith
a
gravitybe
the
same
on
earth's surface ?
partsof the 55.
thingson
space
at the
is its mass
?
water
were
placedat
rest in
a
gravity of the earth,and the vessel should suddenly be annihilated, what would happen to the liquid ? 56. What is meant by.the statement that a body weighs 10 lbs. ? 57. A body 4000 miles above the earth's surface weighs 4 lbs.;
hollow
what
How
58.
gravityof between 59.
if the
that
latitude has
what
At
61.
State two
reasons
than in New
63.
of
Give two
'Why
earth's
its surface would
on
that the
the
centers
of
stress gravitation
densitywere
doubled,the weight of
be doubled.
body its greatestweight at sea-level ? treal why the force of gravityis greater in Mona
Orleans. reasons
why weight varies with latitude.
weightof
is the
gravityat the
between
one-third ?
become
them
60.
62.
the distance
bodies be increased in order
two
body
every
fold must
many
Show
of
centre
a
place? drop at the
body at
the equator less than the force
same
64. If you pieceof paper let
of the
same
same
instant
a
5-cent nickel and
diameter,which
will reach
Digitized by
a
cular cir-
the earth
6
GRAVITATION.
first?
fall in
If both
Why?
a
which
vacuum,
will
fall faster?
Why? to
undergo a change if a body were transported its weight ? of the poles,its mass or the value of pr be the If the earth were a perfectsphere,would Which
65. one
66.
would
not
at all latitudes?
same
67.
If the earth
diameter, and
were
homogeneous sphericalshell
a
hole extended
a
surface to
from
surface
8000
miles in
through the
center,and a ball were dropped through it meeting with no resistanoe from the air,through what part of its journey would its velocitybe accelerated? 68.
If the earth
69.
cut ? rope within, what would happen if the rope were If there is any particle of the earth that weighs nothing and
by
were
it located?
6, 9, 3, and
than
are
as
7
:
4.
all other
were
pended sus-
bodies,where
is
How
D, are respectively gravityof A and stress between gravitation
the centers
Compare
the
of
D.
C and
sea-level is the force of
at Lat. 40"?
72.
body
bodies,A, B, C, and
8 ; the distances between
B with that between
71. At
weight of
of the
cause
of four
masses
fi,and C and D, and
a
Explain.
The
70.
and homogeneous shell,
a
a
yet is apparentlythe
A
retarded?
uniform?
gravitygreateror
less at Lat. 2(P
Explain.
does
stress gravitation
the distance between
their
centers
bodies compare of gravityvaries as 2 : 3? between
two
when
weight of a body in a balloon 5 miles above the sea, its weight at searlevel being 100 lbs., and the distance of the sea-level from the center of gravity of the to be 4000 miles. earth being assumed of a 74. What apparatuswould you choose to ascertain the mass 73. State
proportionwhich will
a
find
the
body?. 75. No on
the
balance
top of
a
is sensitive
mountain
than
that there is a difference in 76.
Airy
found
that
enough
in
at
to show
its base ;
that
a
body weighs less
how, then, do
we
know
weight? a
mine
384"
deep, a second's pendulum
oscillations in 24 hours than at the surface of the earth. 2^ more ? At which placedoes a body weigh more 77. If the earth's axis were produced upward in our hemisphere,it would piercethe sky near (now, at the furthest,about 11") what star? [Thispoint is not in the horizon, but nearlyhalf-way between the made
byGoogk
Digitized
6
EXERCISES
horizon and the zenith ; the observer.] 78.
line
Imagine a
this star to meet
ue.
IN
it is at
an
commencing
PHYSICS.
elevation
equal to the latitude of
at the zenith and
the visible horizon; how
passingthrough
this
horipoint in the zon does a magnetic needle,at your placeof residence, point? is given to the point in the sky vertically 79. What name head overi.e. where line direction of the the a person, produced point of ; ? the would upwards, pierce sky [The point oppositethis is called the nadir.'] 80.
A
81.
How
lbs.
of 100
mass
would
much
weighs how
the
same
near
much
at the earth's surface?
weigh 4000 miles above
mass
the
earth's surface ? 82.
certain
A
body
at the surface
ounces;
at the surface
of the sun,
of the
would
moon
nearly28 tons;
weigh 10
at the surface
of
of this body? the earth,1 ton ; what is the mass 83. How do you account for the difference in weight at the different bodies ? 84.
about
the surface average densityof the earth's crust near three times that of water; the mean densityof the earth The
is is
is probablyas great as 5.58 ; at the earth's center the density in a fluid that of copper. On the supposition that the earth was once about
or
liquidstate,how
Why
could
times farther than Would
a
person the
on
on
the
87.
The
the
were
densitytoward
a
earth's
same
as
throw
moon
earth, using the
person weigh more zenith than when it is in his nadir ? 86.
of
the center
for ?
be accounted 85.
might this increase
densityis
or
muscular
less when
the
about
three
exertion? is in his
moon
?
Why
5.58 times
that of water, what
same
stone
a
; if its
that of water
would
be your
density
weight?
placesof different latitude be compared by sending the same springbalance to the two places? difference would it make in your conceptionsof a pound 89. What educated at the equator or at one of the poles force whether you were of the earth ? About J per cent., providedthat the pound-masswere the at the two places. same ? account of gravity 90. Does a balloon rise in spiteof gravity, or on 88.
Can
91.
Two
the
masses
of two
bodies,one
at
level,have the many
times
as
same
much
bodies at
the other sea-level,
weight ; which
has
more
2000
miles
in
matter
above
it,and
sea-
how
?
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Digitized
MOTION.
3 lbs. and weigh respectively be located that it will weigh the same as
the latter
stress between there Ioteigravitation
On
94.
what
does the
MOTION. K
95.
go in
a
may
the former ?
that
them?
weight of
a
body depend ?
MOMENTUM.
"
9 lbs. ; where
of celestialbodies furnish
evidence do the motions
What
93.
7
IMPULSE.
"
bodies
Two
92.
MOMENTUM.
"
"
snail crawl at the rate of J inch
IMPULSE.
a
second, how
far will it
hour?
an
If
96.
that you
on
are
pass a steamer going in the going,in what direction will the steamer the
ocean
direction
same
you
to be
appear
moving ? 97.
do
we
When
we
consider motion
with reference to time, what
term
employ?
98.
What
99.
What
of every change of momentum and distinction do you make between momentum
100.
What
is a unit of momentum
is the assumed
?
cause
It is the
?
ity? veloc-
of
momentum
one
of one foot per second. pound of matter moving with a velocity 101. Suppose that as a railway train passes a certain point a nimiber of persons should jump off; how would this affectthe train's momentum? 102. Suppose that as a train passes a certain point a number of persons of the train? jump on to it ; how will this affect the momentum 103. How will it affect the velocity of the ^rain ? 104. A shell at rest bursts into two parts,the smaller of which is one-third of the whole ; what of the parts? 105.
If
a
shot
velocityof 1200 106. bodies
weighing
ft. per
Let the
sam"
108.
second, find the
a
gun
weighing3
velocityof the
force act for the
same :
tons with
length of time
1 ; in which
a
gun's recoil. on
two
will it generate
?
the greater momentum bodies
20 lbs. leave
in the ratio of 10
having masses
107. What
will be the ratio of the initialvelocities
will be the ratio between
the velocities which
the two
will acquire? A
person
earth's momentum
leaps from which
his
the
earth; describe
the
change of
the
leap occasions.
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8
EXERCISES
109. He
IN
to the earth
retams
by
PHYSICS,
the action of
gravity;describe duringhis descent.
which occurs change of the earth's momentum 110. The impulse of a force is the product of which it acts, ft mv. Change of momentum
the
force into the time
a
is
=
to proportional
what? little? Why is the impulseof a blow comparatively 112. A heavy man pushes or pullsa child. It is difficultfor ners beginis subjected in science to comprehend that the man to an equal mentally experipullor push. Suggest some way by which it may be shown of that this is true beyond a doubt, using two boats, one of the which together^v^h the child has the same the mass mass as 111.
other boat and 113.
the
If there
combined.
man
were
no
external
which would resistances,
requirethe motion),a body having a mass of
to put in greaterforce to start (t.e. of a pound or a body having a mass
LAWS
OF
114. State Newton's
Laws
ton ?
a
MOTION.
INERTIA.
"
of Motion
verbcUim
et literatim.
Lex
1.
uniforperseverare in statu suo quiescendivel movendi miter in directum,nisi quatenus illud a viribus impressis cogiturstatum
Corpus
omne
mutare.
suum
Lex
II. Mutationem
motus
alem proportion
vi motrici
esse
im
lineam rectam qua vis ilia imprimitur. pressse et fierisecundum Lex III. Actioni contrariam semper et sequalem esse reactionem ; sive corporum duorum actiones in se mutuo semper esse sequaleset in partescontrarias dirigi. 115.
li
a
116. What
Latin student,givea literaltranslation of the above. is given signification
to
the
term
by modem
motus
? physicists
117.
Show
that the firstand second
laws of motion
are
ollaries merelycor-
of the second law.
Why is it dangerous to jump rapidmotion ? 118.
in
119. 120.
How
Why by pullingon
do the actions of two may his
a
man
out of
bodies
raise himself
by
on
a
railwaycarriagewhen
each other
means
of
a
compare?
pulley,but
not
boot-straps?
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Digitized
COMPOSITION
121. A sled
OF
which
on
motion,leavingthe child of the child?
?
body
Is inertia
cannot
a
third law
put
The
bodies interact
two
in any way
or
of motion
derive
?
nature
A
as
of
stone
a
states virtually
why
reason
a
which
is in the act of
in a buggy, can Sitting feet againstthe dasher? Why?
generated in
that all interaction of
stress
127.
Steam
a
to
126. State the third law of motion, and show case
prevent its
produce,or tend to produce, be appliedto their mutual action ?
so
to
name
third law of motion
bodies is of what
the
rapid
Is this due to the inertia
itselfin motion.
motion, what is a suitable 125.
in
force ?
Newton's
When
124.
sitting
the child's inertia hold it back
From
123.
is suddenlyput sitting
the ice.
on
9
MOTIONS.
Yes.
122. Does
moving
child is
a
AND
FORCES
how
it holds
the earth.
towards falling
put it in motion
you
good in
by pressingthe
closed vessel presses with great force the vessel ? Why ? againstthe side of the vessel ; does it tend to move 129. If a hole were would there be a made in the side of the vessel, 128.
motion ?
tendencyto 130.
is "every body of matter possesses inertia," of what fundamental law ? of the universality predication maintains the motions of the planets?
The statement
to equivalent 131.
What
132.
Do
If so, when
a
that
approve
you
is it overcome,
the inertia of 133.
a
When
a
a
of the
"to expression,
and how
inertia"?
overcome
greata force is requisiteto
come over-
body ?
force is said to
overcome
the inertia of
a
body,is not
? only change produced by the force a change of momentum 134. A carriageis suddenly stopped,and the passengers are said to be thrown out ; are they thrown f 135. Is their separation due to inertia ? If they from the carriage were thrown, would a force be necessary? Is inertia a force ? actually
the
"
"
COMPOSITION 136.
When
the
AND
FORCES
forces act in the
same
MOTIONS.
their resultant is direction,
theyact in oppositedirections,their of each of the two forces. intensity
17 lbs.; when
Find
two
OF
resultant is 3 lbs.
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Digitized
10
EXBECI8ES
What
137. in
PHYSICS.
IN
evidenoe would
requireto determine
you
that
body is
a
? equilibrium 138. What
greatestand least resultants of two forces of 7 lbs.and 5 lbs.,and how must they act to produce these resultants? 139. A certain body is pulledin a certain direction {e.g.toward and pushed in the same the E) with the force of 10 lbs., direction with It is also pushed in the oppositedirection (i.e. a force of 15 lbs. toward
the
the
are
with
W)
a
force of 25 lbs.
What
is the resultant of these
forces? What
140.
may
be the directions of two
must
be the
greatestpossible?the P and Q, act 141. Two forces,
lbs. ; Q
a
on
possible? point at rightangles;P=
16
63 lbs. : find R.
=
142. How upon
least
forces that their resultant
body
a
may
be
kept
at rest when
a
coupleis acting
it?
If
143.
elevator ascends with accelerated
an
pressure exerted
by
weight? Why? 144. Show why along which 145. Give
a
146.
is acted
body line straight by forces body remain
his
the road
pulls. compositionof
being uniform,
Is the resultant motion
A
with
platform compare
to ought always to be parallel
illustration of the
angle with each other,one accelerated.
the
on
passenger
the traces
horse an
a
will the
how velocity,
upon
of 100
rectilinear
lbs.,48
or
time
lbs.,and
motions
the other
and
at the, same
two
50
at
an
uniformly
curvilinear? in the
and
lbs. only;
can
same
the
at rest ?
147. State how
having intensities of 75 lbs.,28 lbs., and 47 lbs., can respectively, produce equilibrium. 148. State some which force of 10 lbs. can be made to a way by lbs. 100 with a force of produce equilibrium Find the magnitude and direction of the resultant of two 149. equal forces actingat an angle of 90" with each other. 150. A uniform rod 12 ft. long and weighing 4 lbs. sustains a
weightof center of
12
Where
a
lbs. at
end
one
and
men
pole 15 must
carry
a
block of iron
ft. long ; each
the block
18 lbs. at the other.
hang
Where
is the
?
of the whole gfravity
151. Two from
three forces
man
weighing 176
is 18 in. from
in order that
one
man
lbs.
suspended of the pole.
his end may
bear f of the
weight ?
byGoogk
Digitized
COMPOSITION
152. 153. 30
Explainwhy a shipcan sail A body has two motions,one
ft. per second, and
second; what 154.
FORCES
OF
moving
close to the wind.
very
east with
a
uniform
.
of velocity
velocityof
60 ft. per
velocity? retardation of 10 ft.has, when
uniform
with
of point, a velocity
certain
passing a
11
MOTIONS.
south -fcrith a uniform
one
is its actual
train
A
AND
300
ft.
How
much
farther
will it go ? 155. of what
A
body moves
in
a
circular orbit.
kinds of motion
two
?
In what
Its motion
is
a
compound
direction is each motion
?
Suppose that the velocityof a stream is 4 miles an hour, and hour in still water j a vessel to be sailingat the rate of 10 miles an what is the actual velocity of the vessel if sailing What up stream ? is its velocity if sailing down stream ? from the window of a railwaycar157. If you extend your hand riage in rapid motion direction will it and let drop a ball,in what to fall,and in what direction will it reallyfall? seem 158. If a person is riding on an express train at full speed, in what direction should he toss an apple up that it may return into his hand? (Quote Newton's law which appliesto this case.) 159. A weightof 15 lbs. is carried by two men on a rod 8 ft. long. The weight is hung from the middle ; one is 1 ft. from one end man of the rod, and the other '2 ft. from the other end ; find the weight 156.
borne
by
160.
each.
A
tends
body
to
with
move
equal velocities of
10 ft. per
ond sec-
angle of 120" with each other ; find its 1'. path and resultant velocity, employing a scale of J of 1" 161. A body,while moving in a certain direction with a uniform velocityof 10 ft. per second, is urged in a direction at right angles with the direction of this motion by a force which produces a uniform 1' acceleration of 5 ft. per second. Represent on a scale of J of 1" the two motions during the first three seconds that the force acts and in two
directions at
an
=
=
their resultant motion. 162.
Find
act that the 163.
the distance from
body
Locate
the
point where
the
force
begins
to
attains in three seconds.
point A on paper. Represent by lines and 8 lbs., 6 lbs., AB, AC, and AD three forces of 4 lbs., respectively, two forces actingin the same no actingon this particle, straightline. and direction of Use a scale of } of 1'' 1'. Determine the intensity a
particleby
a
=
the resultant force.
byGoogk
Digitized
12
EXERCISES
164. a
it is
how
Show
possiblefor
Draw
weighing24
bar
it may
horizontal
a
in
rotate
vertical
J of 1 in. produce equilibrium. on
a
scale of
166.
Two
bear
men
to make sailing-vessel
dimensions,hinged at
in
way
their shoulders
on
of the
density. One pointsin the beam
beam
a
so
that
line draw that
of uniform
will
sions dimen-
supports { of the weight.
men
the
may
end
some
line to
a
one
horizontal
pointin the representa force
plane. From 1 lb.
=
and
what
a
line 4 in. long to represent a
lbs. of uniform a
PHYSICS.
that of the wind.
directiou different from 165.
IN
supports be appliedso
as
At
to fulfil
the conditions ?
CENTER
167. What
pointin
a
body
the line of direction of
a
body?
168.
Has
169.
Can
than
body more
a
and
one
what
point in
center
of
the
earth determine
gfravity?Why?
Can you point to the center of gravityof the earth? to the center of magnitude of the earth? What simple
point apparatuswiU assist you
you
GRAVITY.
OF
170. If you
in
to load
were
pointingto the former ? a wagon high with furniture,where
would
placethe heaviest articles and where the lightarticles, having no the to but of turned? regard breakage, liability being overonly considering you
Why? 171. What
do
you
understand
by
the
center
of
gravityof
line
direction
the
earth? 172.
How
the force of
173. its center
When
can
you
determine
gravitybetween the center
the exact
or
in which
body and the earth acts ? of gravityof a body does not coincide with a
of
magnitude, where is its center of motion ? 174. In raisinga ladder with one end on the ground, why does increase with the hightwhich it attains? the difficulty line includingthe 175. What would you give to a straight name C.G. of a body and the C.G. of the earth ? 176. To support a body by a singleforce,where must the force be applied? What must be its magnitude ? In what direction must it act? 177.
Why
are
"
"
top-heavy
bodies
unstable?
byGoogk
Digitized
14
EXERCISES
IN
PHYSICS.
of gravityat the surface of the planet Jupiter intensity being about 2.6 times as greatas it is at the surface of the earth,what the value of g) at the surface must be the acceleration per second (t.e. of Jupiter? bodies whose 7 : 3 mutually attract each 197. Two masses are as other,causing an acceleration in the largerof 10 ft. per second ; find The
196.
the acceleration of the smaller.
in the
body under the influence of
A
198.
eighthsecond
a
force
constant
moves
570 ft.
; find the acceleration.
F, will body projectedvertically up with a velocity, seconds? (b) will reach what hight? (c) will fall in rise how many what time? (d) will acquirewhat velocity? 200. How of long will it take a fallingbody to acquire a velocity ? 32 ft.) 500 ft. (g 201. One stone falls 81 ft.,and another 49 ft.; both reach the their instant. Find the interval of time between ground at the same 199.
(a)
A
=
starting,i see. 202. A body is 10
seconds in
long. How
it roll the
far did
velocity? 203. A body rolling dowti velocityof 20 ft. 204.
A
a
an
minute; how
body moves
24 and
rollingdown
inclined
an
first second?
inclined
What
plane 50
its final
was
plane acquiresin
ft.
a
minute
a
far has it rolled? 30 ft. in consecutive minutes
long
; how
moving with uniformlyaccelerated motion ? will the velocity of the body be 180 ft.per minute ? 205. When is fired horizontally at a hight of 25 ft. above a 206. A cannon lake; how soon will the ball hit the water? 207. The value of g on Jupiter is about 83.7 feet. How long would it take a body to fall on Jupiterfrom a hightof 200 ft.? 208. A balloon is ascending with a velocityof 30" per second; the edge of the car lets go a penny. In what a person reachingover has it been
direction does the penny move at first? 209. A body is thrown of 90 ft. per up with an initial velocity Find its positionat the end of the third second. second. 210.
Given
32 : of 80 ft. per second, where ^ upward velocity Find (a) time of rise;(6) hightrisen; (c) time of reaching ground; id) velocityon reachingground. 2 J'; 100 ft.; 5"; 80 ft. per sec. 211. With what velocity should a body be started from the surface an
of the earth in order that it would
=
reach
the
moon
A
?
body having
byGoogk
Digitized
15
ACCELERATION.
initialvelocity of 40,781 ft. per second directed toward the moon reach the center of attraction and would would fall thence to the an
moon.
Kystrom's Elements
"
212.
of
What
would velocity
What
velocitywould
Mechanics,p. 304.
it attain
on
reachingthe
moon
?
7468 ft.
sec.
per
213.
it
if attain,
on
reachingthe
center
of
attraction it should fall back to the earth ?
Why would the velocities be different ? 215. A body is projected vertically up and rises 4 seconds; at the instant that it reaches its greatest hight another body is projected upward with the same that the firsthad. When will the initial velocity ? two bodies have the same velocity 216. A stone projected with a velocity of 20 ft. per horizontally 214.
second from what
the top of
the
the air?
Suppose that
217.
ground after 3 seconds ; if it meets with no resistof the projectile ance strikes
tower
be the random
would
from
a
starts from
a
a
body
state of rest and
the
imder
action of 20
traverses
a
constant
ft. in 5 seconds
; what
1.6 ft. per sec. the acceleration per second? 218. If the acceleration be 10 ft. per second,throughwhat must
a
body move
219.
How
from
does the
of the twelfth
end
second
compare
a
is
space
of 180 ft. per second ? velocity at the body fallingin a vacuum at the end of the with its velocity
rest to obtain
velocityof
force
a
fourth second ? 220.
A
body
is
at all pointsin its
the
same
221.
what
was
upward vertically projected
path in risingcompare
; how
does its velocity
with its velocity as it passes
pointsin falling? A body projectedvertically upward rises 120 ft. in 1 second ; is its velocity at the end of the its initialvelocity?What
first second ?
136 ft. ; 104 ft.
of 120 ft. descendinga shaft of a mine with a velocity the bottom in 2 seconds ; per minute,drops a stone which reaches 222.
A
man
through what
distance did it fall?
body fall in } of a second ? A weight of 50^ is suspended by a stringfrom 224. the car of a acceleration of 40"" per balloon which is ascending with a uniform second ; what is the tension of the string? is the average velocity of a falling 225. What body during the 223.
What
eighthsecond
distance will
of its descent
a
?
byGoogk
Digitized
16
EXERCISES
If
226.
weightsof
A
227.
3 and
5 lbs.
connected
are
will be the
pulley,what
a fixed passes over 8 ft. second?
PHYSICS.
IN
by
velocity generated each
lbs. rests upon a table ; pulleyat the end of the table. A
body weighing 28
to it passes
over
a
at the other end
stringattached weight of 8 lbs.
a
stringpullsthe body. Find the
produced if
be
that would
of the
stringwhich
a
there
were
resistances
no
acceleration 32
(jg =
ft.).
7Jft. A
228.
downward body projected vertically
second,reaches the ground projected?325} ft. per
a
many seconds must of 1000 ft.per second ? velocity
in
How
230.
A
balloon
man
onds drops from it a stone which reaches the ground in 4 secthe hight of the balloon when the stone was dropped. body is projectedupward with a velocityof 50 ft. ; how
a
; find
231. many
A
is
body fall
of 12 ft velocity it what hight was a
229.
when
a
risingwith
a
of velocity
to
acquire
ft. per
second,
vacuum
a
32.2
seconds will it rise ?
232. may
with
in 3 seconds ; from
With
what
must velocity
body be projected upward
a
that it
rise 80 ft.?
Is there any difference in the velocity which a falling body w hen from certain the a near dropped hight acquires, equator, and from the same hightnear one of the poles? Why ? 233.
234.
force at
of a body under the action of a constant velocity the end of the tenth minute,if its acceleration is 20 ft. per What
is the
minute ?
moving
stone is let fall from
A
235.
} of
at the rate of
a
top of
the
mile
a
a
which railwaycarriage
minute.
tenth of
a
horizontal distance
What
and what vertical distance will the stone have
is
passedthrough
the resistance of the air? second, disregarding
in 4.4
one-
ft.;
0.16 ft.
dropped from the top of a tower, one of them 3 seconds before the other ; how far will they be apart 5 seconds after 236.
Two
the first was
balls
are
let fall? is meant
by sayingthat
237.
What
238.
How
239.
Compare a body'smomentum
of its fall with 240.
How
is the
=
of gravityat intensity at the
its momentum many
g
times
as
many
32.2 ft.? any
placeexpressed?
at the end of the third second
beginningof seconds
the third second.
must
body fall
a
in
byGoogk
Digitized
a
17
ACCELERATION.
of 100 ft. per acquirea Telocity
to
vacuum
second
as
to
acquirea
city velo-
of 20 ft. per second? 241.
How
242.
How
times as far must the body mentioned many questionfall in the.firstinstance as in the last? is force measured
in the last
in the Absolute
System? 243. Explainthe difference between the practical (orgravitation) and the absolute units,and what advantage the latter have over the former
?
244.
In the Absolute
weightof
the unit of
245.
At
246.
What
System the unit of force is what part of the ?
mass
Paris 5^ 9.8094". in Paris is a dyne?
mass
What
=
part of
the
weight of
a
gram-
is the local
gravitationunit of force where you live? It is the weight of a pound-mass at that place. 247. Express in dynes the force which acts on one gram-mass where ^=9.8". 248. What acceleration will a mass of 20 dynes produce on a mass of 10"(F= ma)? ated 249. A body having a mass of 6" moves with a uniformly accelerof velocity 250.
If
a
is the force ?
30"" per second ; what
poundal
act
on
a
pound for
s
second, what will be its
velocityat the end of a second ? it to 251. What force acting on imit mass for unit time will cause with unit velocity? move 252. A force of 500 dynes acts on a body for five seconds and gives it a velocityof 40^ per second ; what is its mass ? 253. One poundal equals13825.38 dynes. How dynes is the many force of gravity acting on a pound of matter in this latitude at sealevel? 254.
gives it
A
force
constant
a
of velocity
A
force of 8
acting on
a
mass
per second ; what
18^
of 20^ for two is the
seconds
of intensity
the
force? 255.
4 seconds 256.
?
yi^*" per
What
first second
dynes acting on
?
in impartwhat velocity
sec.
force will 2800
l^s will
cause
a
mass
of 70k to
20^
move
dynes.
weight of 4s in absolute units ? 258. A of 50c for dynes acts on a mass ? will be produced what velocity 257.
What
in the
is the
force of 200
one
second ;
byGoogk
Digitized
18
EXERCISES
259.
A
gives it
PHYSICS.
force of 20
constant
of velocity
a
IN
of 40b, and dynes acts on a mass seconds did it per second; how many
150"
act? 260.
A
force of 100
dynes actingupon
a
acceleration per second ? acceleration will a force of 56 261. What
of 600^
mass
will produce
what
?
14"" per
262.
How
263.
A
? 264.
far will the above
body whose
2} ft.per What
4s produce
sec.
30 ft. from
moves
dynes actingon
a
in 10 seconds ?
body move
is 15 lbs. acted
mass
on
state of rest in 5 seconds.
by
a
What
700"". force
constant
is the acceleration
sec.
is the force
employed in
the
last example ?
36
poun-
dals. 265.
If
a
mass
of 10 lbs. is acted
on
by
two
oppositeforces of
poundals,what is the acceleration? 266. How long must a force of 8 units act on a mass from 2 to 26 per second (mv =Jt')'i change its velocity and
36
267. radius. moon
28
?
The
radius of the moon's
orbit is about
80 times
of 20 to
the earth's
What
acceleration does the earth produce on centripetal
About
0.0089
ft. per
the
sec.
PENDULUMS.
body be so suspended at some point(^4)in it as to swing of vibrations in a given like a pendulum, making a given number time,there can always be found another point {B) in the body from which if it be suspendedit will make an equal number of vibrations time. in the same When the body is supported and oscillated from either of these points, what is the other pointcalled ? would be the lengthof a simplependulum that would 269. What vibrate with equal rapidity? 270. If the body is supportedat either of these points, where may the body be struck without producingpressure on the support? 268.
If
a
clocks,one in latitude 10^, the other in latitude 40", both at sea-level, have pendulums of the same length. Which will gain on the other,and why ? the greater 272. Where will a pendulum of a given lengthmake 271.
Two
byGoogk
Digitized
CENTRIPETAL
of vibrations
number
in 48
19
FORCES.
hours, at the equator or
at
a
pole of the
earth?
lengthof
273. The
a
second's
pendulum
-^;what
=
is the
length
pendulum in our latitude in inches ? in centimeters? 274. A pendulum beats seconds. Required the value of ^, if the same pendulum beats 50 times a minute. }| of the normal value
of
second's
a
of ^. A
275.
about
27.6
body weighing 1 lbs. at the
lb.
the earth's surface
on
surface; what
sun's
weigh
would
acceleration per second
does the force of 276.
A
gravityproduce at the sun? pendulum which vibrates seconds
between
make
5
and
vibrations
6
per
the
at
second
at
would
earth
the
plain. Ex-
sun.
2/
277.
From
the formula
in Spitzbergen, 278.
which
Explain what
a
9=
compute the force of gravityat
"^
second's
is meant
pendulum is
by
0.99613"
the statement
long. length
that the real
pendulum is less than its apparent length. 279. A certain pendulum in a certain place beats seconds exactly, in another placethe same pendulum gains just one vibration in 48 hours; at which place is the force of gravitygreater? How many times greater? 280. A pendulum one-fourth as long as a second's pendulum will of
a
make
how
281.
A
in winter.
vibrations in
many
clock In
a
minute
having a pendulum
summer
it loses 2
?
39.09 in.
long keeps correct time minutes per day. How much has the
pendulum expanded in length?
CENTRIPETAL 282.
If there be such
radially away to
the
from
a
FORCES.
thingas
the center, and
centripetal force,would
the
a
force urging a body centrifugal
this force be
body
equal and in
orbit
opposite or
in
a
tendencyof matter to move given to the reaction straightline,"or is it a convenient name force which deflects a moving body from a straight path ?
in
a
move
an
line ? straight 283.
Is
force centrifugal
"'a
of
byGoogk
Digitized
"
20
BXBKCI8B8
is said to be
Mud
284.
wheel.
285.
a
thrown
'
PHYSICS.
off
that it is not thrown
Show
due to
*"
IN
"
from
off,and
the
or any other force centripetal, centrifugal,
A
circus-rider going around
the line of direction of his
reyolyingcarriage going off is not directly.
that its
ring inclines
a
body falls without
inward
his base.
that
so
How
is he
supported? 286.
State the conditions and
shot
a
zontally might be projectedhori-
fallto the
ally. earth,but travel around the earth continubody travelingaround the earth on similar conditions?
never
Is there
which
on
a
287. Describe the two
which
motions
result in
keeping the
moon
in its orbit. 288.
What
name
moving body to
move
is
givento
in
a
the
force which compels a deflecting curvilinear path ? Why must it be a continuous
force? 289.
What
290.
A
is the
body moves
force act, and in what
force in planetarymotions ? centripetal in a circular orbit;on what does the centrifugal direction does it act?
force is proportional to the square Centripetal (or centrifugal) of the velocity only when this force acts at what angle to the path of the moving body? 292. If a ball suspended by a stringis made to revolve about the the hand, and the stringbreaks,is it broken by the centripetal or 291.
force ? centrifugal 293. If the earth
to
were
value of g at the equator be 294. In what time must
greateror
295.
How
is distance
"
or
24
WORK.
on
its axis,would
less than it now
the earth revolve
equator will weigh nothing? 1 h.
ENERGY.
to rotate
cease
42^
m.
"
so
is ?
Why
the ?
that bodies at the
sec.
POWER.
length representedin
the C.G.S.
tem? sys-
L. 296. 297. 298. 299.
How
is area
represented? LK ? Z". How is volume represented ? How is density ML-\ represented ^Vhat does the expressionML-* mean?
Mass
divided
volume.
byGoogk
Digitized
by
22
EXERCISES
If
316.
body of
a
the action of kinetic
IN
M
mass
move
force F, what
a
PHYSICS.
over
a
space
the
will be
SmT
seconds,under
gain in
momentum
and
energy?
317. If ^ 10 lbs. with 318.
32.2
=
a
What
ft, find the equivalentof heat necessary
to
project
of 800 ft. per second. velocity quantityof energy will a force of 10 lbs. generatein
actingthrough a space of 75 ft.? 319. A body weighing 10 lbs. projectedvertically upward with initialvelocity of 64.4 ft. per second will rise 64.4 ft. Using the an formula, Kinetic
energy
=
"
"
or
"
-"
,
compute in foot-poundsthe
kinetic energy which the body has at the start. FS or RS^ compute in 320. Using the formula, Work =
the work
done
on
the
body
named
foot-pounds
in the last question; in other
words,
does potential energy stored in it while it is raised 64.4 ft. How with the the kinetic energy lost by the body in ascendingcompare the
potential energy gained? air,which of the in the last question will be greater? two kinds of energy named 322. A train moves at the uniform rate of 30 miles an hour against Find the horse-powerof the engine a constant resistance of 1600 lbs. drawing it. 323. A man does 1,056,000ft.-lbs.in a working day of 8 hours. At what fraction of a horse-power does he work on an average? from a cloud one324. What would a drop of water falling velocity 321.
half of
If the
a
mile
meet
body
with resistance from
"ighattain
if it were
the
with
to meet
no
resistance from
the air?
drop of water weighs7^ of a j^und. What kinetic energy would a drop of water acquirein falling from a cloud one-half of a mile high if it were to meet with no resistance from the air? 326. What ? is a man-power A power capableof doing3000 ft-lbs. 325.
A
Morin, per minute. much work at this rate will 327. How
of work
"
a
man
do in
a
working day
of 8 hours? 328. 329. uniform he
How
are equivalentto a horse-power? many man-powers A horse is drawing a wagon along a horizontal road at the rate of 5 miles an hour. What becomes of the work which
performs? 330.
What
is vis-vivaf
The
productmv^,the double of the kinetic
Digitized by
BNEBGY.
energy of
a
(^^),
body
WORK.
"
formerlycalled
was
23
POWER.
"
its vis-utVa.
The
term
is
nearlyobsolete. 331. Define a muscle,from a dynamic standpoint. It is a machine into kinetic energy. for transformation of potential much work must be done in order to give a stone weigh332. How ing 2 lbs. a velocity of 100 ft. per second? of 10 ft. per 333. A body weighing10 lbs., moving with a velocity will ? second,must do how much work before it stop now
334.
Why
is the energy due to the motion
not available to
335. Make
us
of the earth in its orbit
?
three
equationsfrom
the
viz. : F, followingquantities,
FtyFSf mv, imv^, 336. will
Designatetwo
of the
either one foregoingquantities,
blow ; and two
blow ; two which will represent the which will representthe average force of a
certain author
in his treatment
representthe impulse of of
energy
a
of which
a
blow. A
337. "
makes
use
of the
: followingexpressions
"*
'*
"
chines ma-
An
for an intensity exchange velocity of power." " The power multipliedby its velocity equalsthe weight word should be substituted for multipliedby its velocity."What ? energy in the firstquotation 338. In the second quotationwhat name has he given to the same agent? 339. Has power velocity?See the third quotation. 340. The same author declares that energy is the power of doing work," and that the rate of doing work is power." To what three distinct entitiesdoes he apply the term power ? 341. A body weighing 2*^, of 40" per second, moving with a velocity has how much kinetic energy? A
"enables
subjectof
energy of small distance may be made to reappear," sity." energy of considerable inten-
actingthrough a considerable intensity of a machine, as an by means machine
of the
us
to
"
"
342.
Has
343. Is
energy,
much
work
capableof doinghow
344. When 345.
had how
What
done much
upon
it?
work?
stoppedwill generatehow much is meant
usuallyin
heat ?
by degradationof
the form
of heat,so
as
of energy ? A dissipation to be unavailable for work.
byGoogk
Digitized
24
EXERCISES
is the technical
346. What done
by any agent in
347. What created
or
PHYSICS.
meaning of
unit of
a
is
name
the word
time, power; "
actimtyf Work
first used
son. by Thom-
given to the doctrine that energy
cannot
be
annihilated ?
What
348.
IN
is givento the doctrine that all forms of energy
name
transmutable ?
are
A well is 40 ft. deep and
349.
is 10 ft. deep. Estimate cubic foot of water
5 ft in
the work
of
and the water in it diameter, removing the water. [One
weighs62.5 lbs.]
? requirewinding up periodically 351. How many times as much energy has wind blowing at the of 75 miles rate per hour than wind blowing at the rate of 10 miles 350.
Why
does
per hour ? 352. When
a
clock
does work
performedon
a
itskinetic energy
body cause
to increase ?
353. When
a
body is not doing work, but
has allthe
of capabilities
doingwork,what do
we say of it? that there is conservation of energy, but
354. Show
no
conservation
offorce. 355. A
sand;
shot
how
at traveling
far could
a
a
certain
bury itself5
speed can
with double that shot traveling
ft. in
speed bury
itself? 356.
How
is the work
necessary to overturn
a
body supportedat
itsbase calculated? 357. a
If
blow with
358.
of
a
an
anvil
hanmier,the person
on
his chest, and the anvil be struck
supportingthe anvil is
not
much
Why?
hurt. Mass
lie with
a man
?
In what unit is work Volume
estimated?
Energy?
Force?
Power?
?
359.
Why
can
360.
How
does
no a
force
destroyenergy ? in 4he motion prevent greatirregularity fly-wheel
machinery? 361. Force multiplied by the time duringwhich it acts giveswhat? 362. Force multiplied by the space throughwhich it acts gives
what? 3"j3. How
is energy stored?
364. Momentum
is the
productof force into what?
Energy is the
productof force into what?
=
1
ENERGY.
365.
Show
to Newton's
steam
is
force
When
does
When
370.
371.
gram,
a
machine,
a
force
"
force,power,
corollary
energy?
or
"
the
or
give to the pistonof
actingon
done measured force does work
body, what
units:
appliedto
the action of steam
is the work
the
a
of Motion.
"
energy
of
steam-engine
a
energy?
or
369.
How
of energy is
force of steam you say that the the pistonof a steam-engine?
Does
25
POWER.
"
moves
368.
Law
Third
367. Would "
"
that the doctrine of conservation
Which
366.
WORK.
"
body
do work
that quantities
that
upon
body
?
? on
body, and
a
is given to the accumulated
name
State the
a
are
measured
work
in
accumulates
work? in each
of the
following
dyne, erg, second, calorie,degree, horse-power,centimeter, pound, foot-pound, kilogrammeter, cubic centimeter, liter,
atmosphere. In
January, 1878, on Mt. Washington, in New Hampshire, the wind attained the extraordinary velocityof 2728 ft. per second. The weight of one cubic meter of air of average sea-level densityis 1.293^ this mass What of air possess having the energy would 372.
velocity given? 373. In terms
ways may the force "of gravitybe expressed? of acceleration or in terms of the weight of unit of mass
In what
two
in absolute measure;
e,g, 980*^" per
second, or
980
dynes
per
gram
mass.
374.
If the
equator, what 375. When 376.
Can
377.
What
ocean
stands
prevents its
13 miles waters
is acceleration termed force be stored is the
higher at the poles than at the from flowing tumultuously poleward? and when positive,
negative?
up?
originof the absolute dimensions
of force?
F=MA,A=^whence F=3fx^.F=|. By substitution,
378. What
is the
originof the dimensions
of work?
byGoogk
Digitized
26
EXERCISES
379.
What
is the
IN
originof
the dimenmons
T
380.
how
Show
the
PHYSICS.
of
power?
T
expression(JLT-^ for the dimensions
of
acceleration is obtained. L
T
T
T
T
MOMENTS. What
does the term
in snch
moment expressionsas of a magnet," moment of a conple," moment of a force," moment of inertia,"etc.,signify? The importance or value of the subject 381.
moment
"'
'^
'*
""
referred to. 382.
Suppose forces of
units of distance
from
8 and
2 to be
the fulcrum
of
a
1 and appliedrespectively
lever
:
do the numbers
4
8 and 4
express the relative value of these forces ? 383. (a) Suppose a rod CD, capable of
turning about the fixed point 2), to be acted on by a force F; the tendency of the force to turn the rod about D will depend on what two quantities? (h) In would you what two ways may this tendency be doubled ? (c) How calculate the moment 384.
When
sum algebraic
385.
of forces any number ? of their moments
If three
what
of the force ?
men
are
in
what equilibrium,
is the
support a triangularplatform at its three
ners, cor-
portionof the weightwill each bear ?
couple? It is the productof one of the lines distance between the forces multipliedby the perpendicular 386.
What
is the moment
the representing 387. Show
388.
Show
a
directions in which
that
lengtheningits
of
the two
the sensitiveness of
a
forces act is increased
balance
by
arms.
that
the
moment
of
a
force
is
greater in
shut-
byGoogk
Digitized
27
MACHINES.
ting a door when hinge.
handle
the
applied at
than
if
applied near
the
doublingthe distance of a force from the fulcrum is as good as doubling the force itself. of a lever,a force of 8 lbs. can 390. State how, by means produce equilibriumwith a force of 96 lbs. 391. A horizontal bar is supported at its center,but is free to rotate about its support; a weightof 10 lbs. is appliedto the bar 1 ft. from its center,and a weight of 1 lb. is applied to the bar on the that
Show
389.
other side of the center
of explainon the principle
long,and from
it.
The
bar does not
move
;
moments.
pole 6 ft. the pole 30 inches a weight of 121 lbs. is suspended from what portion of the weight does each man of the men;
Two
392.
10 ft. from
and
one
men
support? 393. Explain and
their shoulders
on
carry
illustrate what
at its ends
is meant
a
by equilibrium of
moments. 394. a
load
Point on
a
out
the conditions
what
portion of will be supported by the wheel,and what
wheel-barrow
which
determine
portionby the person. rod of imiform knife-edgea wooden of matter diameter loaded at one end with lead,will equal quantities be on the two sides of the blade ? Why ? 395.
K
balance
you
a
on
MACHINES. 396.
397.
Define power. Can Is a gain of work
be obtained
may
398. expense 399. cases
by
the
of the mechanical
one
of
a
machine
use
of any machine? advantages which
?
employ tidal water-power to do work, it is of what energy? The energy of the earth's rotation. When
What
we
is the ratio between
of the lever,screw,
400.
use
by the
gain power
we
How
does
a
and
mechanic
the force and
at the
the resistance in the
windlass ? value
a
machine
?
By
its efficiency.
401. Describe the distinctive
uses
:
and state their followingmechanical movements eccentric, centrifugal spur-gear, bevel-gear, governor,
and escapement.
byGoogk
Digitized
28
PHYSICS.
IK
EXEBCISES
Why will a person accomplishmore in helpinga cart up hill by applyingforce to the rim of the wheel than by pushingj|tthe body 402.
of the cart? If the
403.
of gradient
a
road is three times
greaterin
a
certain
partthan in another,how many times greaterforce must be eniployed in the direcin the steeper tion part to givea certain load a givenvelocity of the incline than in the other
part?
work, a stationary engine of how many horse-powerwould be requiredto draw a car weighingfive tons up an inclined cable road ^ mile long, having a gradientof 8 in. in 10 ft.,in 10 minutes ? 33H h.p. of a band passingpartly 405. Motion is communicated by means wasted Disregarding
404.
around
the circumference
The
B.
circumference
a
wheel
of wheel
axle of wheel B\r
3 in.
giventime?
many
How
of
times
is 2 ft.; the circumference
A
Which
wheel as
Will
OF
air-pumpenable
an
makes
more
wheel of the
revolutions in
a
many?
DYNAMICS 406.
to the axle of another
A
FLUIDS.
you to reduce the volume
of air in
a
receiver ? 407. If of
a
water
mercury barometer barometer?
falls
a
408. Of
what
two
machines
inch, what will be the fall
one
does
the
ordinaryhydraulicpress
consist? 409.
Should
Mechanical 410.
a
bottle?
hydraulic press
proper be included in the so-called
Powers?
Contrast
pressure. 411. Can of
the
the methods
you suck air out
by of
a
which
solids and
bottle?
Can
fluids transmit
suck water
you
out
Why?
it be determined that the average atmospheric may pressure at searlevel is 14.7 lbs. per square inch ? 413. When the barometer stands at 30 in., a cubic yard of air is 412.
How
compressed into
a
pressure per square the box?
cubical
box, each of whose
inch does
it exert
edges is
againstthe
1 ft.
What
interior walls of
byGoogk
Digitized
30 Convert
428.
weigh? weigh ?
Convert
a
pressnie or 430. If
a
down it
would
one
ponnd of ponnd of
; what
water
into steam
steam
into water ; what
liquidcarried over the by its own weight? By
Is
429.
look
one
physics.
ik
-EsasBxyjSES
of
bend
will the steam will the water
siphon by atmospheric its weight. a
atmosphereso as to person could be elevated above our its surface, and the atmosphere were visible,how upon like the
Uneven
appear?
earth's surface,depressed over
of low pressure ; and elevated over areas of high pressure; but the atmospherichills and dales are ahnost unlike the earth's surface, areas
in constantly
motion.
What
431.
is the direction of the wind
Generallyinward
toward
in
an
the center,having a
contraryto the motions of the hands of What
432.
The
is the direction of the wind
of low
spiralmotion a
pressure? in
a
rection di-
clock.
area"
of high pressure ?
of the above.
reverse
What
433.
over
area
isobaric lines
are
equal barometric 434.
Of
435.
For what
what
seen
on
weather
maps?
Lines
of
pressure.
shape are these lines? purpose
onlyshould
elliptical. Generally the student
use
a
barometer?
It will requiremore than wisdom atmosphericpressure. in making to acquirein the schools to use it intelligently he is likely weather predictions. To
measure
What
436.
is the space in the tube
above
a
barometric
column
called?
Why does not the enormous it to collapse? cause soap-bubble 437.
SPECIFIC
AND
SPECIFIC
upon
a
GRAVITY.
atmospheres. Find n (S.G. of air and cork beingrespectively 0.0013 and 0.24). 439. An iceberg(S.G. 0.925) floats in sea-water (S.G. 1.026). Find the ratio of the part out of the water to the part immersed. What 440. A cubic foot of water weighs 1000 avoirdupois ounces. is the weightof 1 cu. in. of mercury (S.G. 13.59)? 441. If 2 cu. ft.of a body weigh 100 lbs., what is its S.G. ? 438.
Cork
DENSITY
atmospheric pressure
would
float in
n
byGoogk
Digitized
442.
Find
443.
What
the
a
S.G. is 9.6,and whose
body whose
lbs. ?
under in
difference 445.
12
Compare
at the
the
same
pressure.
How
do you
ature temper-
same
for the
account
density? in. of
cu.
mahogany weigh
as
much
53
as
cu.
in. of cork.
their densities. vessel is three-fourths full of water
446. A
the bottom
be affected if
piece of
a
; how
will the pressure is submerged in the
metal
until the vessel is full?
water
447. What
weight of
448.
is the volume
What
449. W^hat a
of
S.G. is 0.24.
ft.of cork whose
Oxygen gas is denser than hydrogen gas
and
on
cu.
is the volume
weightis 4200 444.
1
weightof
31
DYNAMICS.
MOI/ECTJLAR
solid
will 10 lbs. of cork
water
displace?
of 1^ of cork ? you choose to ascei*tainthe
apparatuswould
densityof
body ?
percentageof nitric acid 36" Beaumd, 15" C, is HNOs? 54 per cent ; H^O 46 per cent. HNOj in distilledwater,what is its S.G. ? 451. If a body sink f of itsvolume form, 452. The S.G. of ice is 0.918. If a lump of ice is placed in chloroWhat
450.
=
=
it will float with 0.6125
of chloroform 453.
How
suspensionin 454.
A
its
mass
What
submerged.
is the S.G.
?
much a
gram
is the
apparentweight of
a
body
diminished
by
liquid? of lead whose
MOLECULAR 455. Molecules
S.G. is 11.35
occupieswhat space?
DYNAMICS.
of
liquidsexperiencewhen they sUde over one a quantityof resistance^which is analogousto friction. It varies in different liquids, beinggreaterin oil than in water,and less
another
certain
in alcohol than in water.
456. What State
is meant
What
by
the
is the technical of viscosity
a
name
of this resistance?
gas? a liquid?a
phenomenon illustrativeof each.
some
457. Which
is the
the pressure of air in greater, the external pressure? Explain. 458. of
a
solid?
What
name
a
soap-bubbleor
is givento internal friction among
the molecules
body ?
byGoogk
Digitized
32
EXERCISES
What
450.
a
amorphous? 461. State pointsof
brick
building and
a
the line between
between
and
aoln^^ oystal,ciyskaDine^
pointsof
diffisrenee between
both in respectto their eonstitation crystal,
what
by
which
is natural
the result of force directed force
make
you
resemblance
and the methods
and stmctnre
the
meant
distinction do
4(N). What and
thai by the 8tatein0n;t boilingis 3.6?
IS
almost
in water
PHYSICS.
IN
they were
and what
and by intelligence, natural
governed merelyby
is artificial; what
what
in which
laws
ing constructed,drawis
is the result of
has intelligence
no
part Is
462. is rock
a
loaf
sugar
a
or crystalline^ crystal, amoiphons?
Whidi
candy?
463.
Is
onion
464.
Is ice
an
crystal? Is
a
mineral?
a
Is
an
a
brick
icicle
a
crystal? crystal? Is
a
a
snowflake
a
crystal? 465.
State
thousand 466.
pointsof
resemblance
between
all of the
more
than
a
of snowflakes?
forms
at (F C. is denser
Water
the difference of
than
ice.
How
do you
account
for
density?
liquidstend to take a sj^erical shi^? like 468. do not t ake solids, liquids, sjdierical Why shi^ws? 469. Show that the spheroidalform which drops of liquidassume is a phenomenon of surface tension,and not due to the cohesive foice drawing all the molecules as near each other as possible.'* 470. To what force is the spheroidalshi^ of the earth due? 471. What forces prevent the earth being a perfect sphere? 467.
Why
do
**
472. water? 473. of water 474.
Tvhv of 475.
About 75
what
does
?
About
At
what
the surface tension one4hird
What
as
is meant
surface film of
"
of alcohol compare
with thai
great.
distance does molecular
centimeter.
of the
lineal centimeter.
dynes per
How
a
is the contractile force
attraction become
senmble?
Thomson.
ting of gases ? Absorption (or shutup) of gases into the pores of solids and liquids. 476. How occluded gases expelledfrom the poreB of bodies? are
by
occlusion
byGoogk
Digitized
ELECTBICITY.
ELECTRICITY. Does
477.
cnrrent
a
of
consist of electricity
actual flow of electricity?
an
whatever electricity a transfer of electricity, certainly then it is a transportof that fluid ; if it is may be. If it be a fluid, then a current is no material transfer. material, notiiing in doing work, does the energy cease 478. When heat is consumed It is
to
exist,or is it transformed 479. How
is
one
form
into
of
energy?
usuallytransformed
of energy
of energy ? transformations 480. What
otiierform
some
into another
form
followinginstruments,viz.:
of energy
are
achieved
by
each of the
steam-engine,a dynamo, an electric while it a storagebattery, motor, an electric lamp, a voltaic battery, is beingcharged, and a storagebattery when in use? 481. Name
some
electric energy mechanical motion On
instrument
by
of which
means
the
following
viz. : heat into electric energy ; may be accomplished, into heat; electric energy into mechanical motion;
transformations
482.
a
what
into electric energy. does the energy of two quantities
an
electric current
depend ? 483. the
the elements
Ought
of
a
voltaic cell to touch each other inside
liquid? 484.
What
characteristic should
should be rich in oxygen, in with hydrogen. 485.
486.
What
487. What 488.
Make
used for
should it be kept ? wire is suited to such a
drawing of
liquidpossess depolarizing
form which
a
batteryis most
Where
a
a
In a
It
is available for combination
bell-ringing?Leclanch^. an underground cellar.
circuit ?
circuit
?
No. 16
or
18 officewire.
two bells, includinga battery,
and circuit-closer. 489.
Make
490. Make 491. Make 492. What
drawing of the essential partsof an electric call-bell. a drawing of a singlestroke bell. automatic contact-breaker. a drawing of an distinction do you make between statical and dynamical
a
Do electricity?
these
terms
imply
two
electricity? 493. In a given circuit in which the to strengthof current will be proportional
hinds or. two
states
resistance is constant what
singlequantity?
Digitized by
of
the
34
EXEBdSES
404.
An
ampere
is the curreiit
PHY8ICS.
by
gma
RM
an
.F. of
toU
one
lesifltanoe?
throughwhat 495.
IK
Give
illnstration of electric
force; also of electric eneigy. is the best anrangement of Toltaic cells when 496. What the external resistance is extremelysmall ? cannot 497. All science declares that man create (t".produce tricity, something from nothing). If we can produce or generate elecont of what is it produced or generated? 498. Compare the resistances of two wires of the same length and 0.3"" and 1.6"^ in diameter. material,respectively 499. Will a battery give a stronger current when the temperature of its Uquid is 40" F. or 80" F. ? an
"
**
500.
What
minute,
one
501.
will quantityof electricity if
Have
502. What
constant
a
of
current
one
pass
"
'"
througha conductor
in
ampere is maintained?
7 electricity any special sense-organ for appreciating distinction should be observed between electrification
we
? The former is the result of work done, and is a form electricity is not the result of work done, and is not a form of energy ; electricity of energy, but,like matter, it is moved and strained. 503. Why will not a singleDaniell's cell decompose water ? ? does zero potential 504. What mean 505. Does an electricalpump or ''produce*' generate,** electricity? water. than No more a water-pump generates
and
""
506.
How
507. What
you teU the kind of electrificationa machines b"tteries,dynamos,electrical
would are
body has ?
?
Kinds
of
electricity force-pumps. 508.
What
is thoughtto be the function of the wire used in
an
tric elec-
It does not convey electric (etherial) pulses:it directs and preventsthem from spreading out, mudi as a speaking-tube
circuit? them
confines and directs sound-energy. will you show that electro-motive force is not Force tends to move what ? Electro-motive force tends to move 509.
510.
Take
How
How
is Trouv^'s
concentrated
a
force? what
?
liquidprepared? depolarizing
pulv.potass,bichromate in 1 pint of water; shake; then is highly add, dropby drop,63 dr. sulphuricacid. This preparation 21 dr.
recommended. 511.
What
is the
betwe"i two pointsin the
relation between an
the
electric circuit and
difference of
potential
the resistance between
points? Why?
byGoogk
Digitized
35
ELECTRICJITY.
512.
The
mechanical
which
work
given current
a
of
is electricity
capable of doing is dependent on what ? 613. Pass a current through a solution of copper sulphate. Which pole will show a formation of brightcopper? when in use ? 514. Why should glassinsulators be kept warm 515. Glass is very hygroscopic.Why will a coat of shellac improve of glass? the insulating properties 516. What would be the effect of surroundingbattery jarswith ice when working? It 517. In what peculiarcondition is a wire conveyinga current? is surrounded by magnetic whirls. 518. What is the excitingliquidused in a Leclanch^ cell ? 519.
E.M.F.,
What 1.6
the
are
electrical
dimensions
volts; resistance of No.
2
of
cell
a
Leclanch^
cell?
(generallyused),
1.1
ohms. 520. a
What
current
will
No.
a
short,stout copper wire? 521. What current is requiredto 1 amp. 522. What
Leclanch^
2
cell furnish
through
call-bell? From ring an ordinary
j^to
? We is electricity
do not know.
But
we
are
best able
dium explain electrical phenomena by assuming the existence of a mewith certain endowed such gtio^t-mechanical as properties, of volume, possessing or infinite elasticity incompressibility, mobility, of constitution {i.e, doubleness a analyzableby "J!ii.F. into two out allowingbodies to pass through it withprecisely oppositeentities), while its components are elastically attached and resist resistance, forces tending to separatethem, each constituent possessinga property in some respectsakin to inertia. Lodge,
to
"
523.
What
distinction is to be made
and electro-motive
between
matter-movingforce force ? The former acts upon matter,displacing it ; or moving it. electricity, straining
the latter acts upon mass? 524. Has electricity 525.
Is
an
a electrophorus
**
"
? of energy 526. Why
527. Give acid
By
How
of
apparentlyunlimited supply
it furnish any energy ? electrical contacts usually made
Does are a
recipefor
1 lb. ; crystals,
528.
source
water
a
of
platinum? depolarizing liquid.Chromic 1} pts.; sulphuricacid,7 oz. (cold), chromic
exhausted an may addingto it ^ its volume of
acid
bichromate
solution be
improved?
acid. sulphuric
byGoogk
Digitized
36
BXEBCISBS
IN
PHYSICS.
529.
What
is the
530.
What
are
531.
What
is dynamic electricity?
532.
What
is meant
533.
May
of a battery? i.e. what part of the efficiency energy developed by the consumption of the chemicals is available ? 50 per cent when the external resistance is equal to the intemaL
the
induced
currents
?
by joiningcellsin opposition? contact
mere
between
bodies of different kinds
two
between them ? produce a difference of potential 534. In what unit is the capacityof a Leyden jar measured ? 535. How does electricity get through the liquidof a batteryand ? It is probableby chemical decomposition, other electrolytes flowing toith the atoms of matter which travel along and connot throughbut vey their charges ; ue, by convection. 536. How heat and electricity travel ? Only by conduction can or convection. If
permanent difference of potentialbetween two connected by a conductor can be maintained, how long will a flow between the points? 537.
120 revolutions
At
538.
About
?
Holtz machine
per
0.00004
what
minute
is the
current
resistance of
a
2,180,000,000ohms.
is the maximum
539. What About
points
a
current
furnished
by
a
Holtz machine?
ampere. Kohlrausch. of elements connected in series how 540. In a batteryconsisting in the several cells ccHupare ? The does the quantityof zinc consumed in each.
same
541.
branch
542. and
"
is the reduced
What
circuits?
It is the
resistance of four branch
The
10 ohms
; what
543. At what the
What
1.5 volts.
circuits
are
of conductivity
the
4,6, 8, respectively
1.571 ohms.
is their united resistance?
densityis
greatest? S.D. 544.
united resistance of any number of of their recipreciprocalof the sum rocals. or
dilute
sulphuricacid
1.1.
is the
counter
E.M.F.
in the
of electrolysis
water?
Wigan,
"
545.
Should
546.
What
the zinc of
a
is the E.M.F.
Daniell cell be of
a
Holtz
amalgamated? About
machine?
No.
50,000
volts.
speed of rotation of a Holtz machine By decreasingits resistance.
547. How current?
does
increase the
byGoogk
Digitized
88
EXEBCIBES
IN
PHYSICS.
(Le.its rate of doing mechanical work) of a cuient of 3 amperes flowingthrong an external nwiatance o^ 2 ohms, the E.M.F. being 5 volts. 564. A current of 1 ampere will decompose abont 3" of water por hour. How will be decomposed by a corrent of 5 many grams amperes? 563.
Calcolate
565.
What
566.
567. den
telegraphpoles?
on
juice. Why is
the current
in circuit with
when
What
jar; or
have the nninitiated conceived
imaginaryuse
glassinsulators fluid or
the power
is
a
of
Bottles for
Leclanch^
a
?
electric enei^, e.g. a storage celL is the unit of electric eneigy 568. What
What
570.
Can
571.
batterymore
electric
constant
A
condenser, e.g.
a
Ley-
of becoming placeof storageof potential energy susceptible
a
569.
holding the
largeresistance?
electricalaccumulator
an
for the
work?
or
is the unit of electric power? than
more
is not
Why
one
circuit be worked
the so-called frictional
from
singlebattery?
a
used electricity
for industrial
purposes? is the
572. To what of
due?
electric current
an
573.
lamp? twice
as
What
lightproduced in
effect has
The
is positive
fast
as
574. About
a
by the passage
Rarefied gas made luminous. direct current the two carbons of the on
usuallyplacedabove the negativecarbon.
what
tubes
vacuum
is the resistance
and
is
worn
away
of electriclightcarbons ?
about
eter Diam-
9"", 0.78 ohm 575.
They
last
576. Arc
What
per meter when cold. benefit is derived from platingthe
arc
arc
lightcarbons?
longer.
What
lamps
in
prevalentmethods of connectingelectric lamps? series ; glow lamps either in multiplearc or in multiple are
the
series. 577.
How
many
incandescent
lamps requiringa
current
of 1.8
amperes,each having a resistance of 30 ohms, can be operatedin with a dynamo having an internal resistance of 0.05 ohm arc E.M.F.
tiple muland
of OOvolts?
If you had an electric lamp in circuit, and you should intro" in the the fall of potential how would another lamp in series,
578. duce
first lamp be affected? 579.
In
which
case
is
more
heat
generated in
a
voltaic
battery.
byGoogk
Digitized
89
ELECTRICITY.
while the current
is
doing much exterual work, or while it is doing Httle external work? Why? of the following:thermometer, cal580. State the special orimeter, uses barometer, hydrometer,hygrometer,dynamometer, galvanometer, electrometer,alcoholmeter. 581. Is the resistance
lightedthan 582.
when
of
incandescent
an
cold?
curtails the life of
What
less when
lamp greateror
Volatilization
glow lamp?
a
or
ruptureof the carbon. 583.
"*The
into
changed electricity
of
amount
heat
be changed into electricity
or
heat,"etc.
Can
anything else?
is the process of electric welding? It consists of a partialfusion at the surfaces of contact, produced by sending an 584.
What
through the junction. When
electric current to
Of
the surfaces
are
reduced
plasticstate,pressure is employed,which effects the welding. 585. Of what doei^ a system of time telegraphy usuallyconsist?
a
clock controlling
a
and several
secondaryclocks.
secondaryclock consist ? Of a dial and an device for moving the hands electro-magnetical step by step at the 586.
Of what
does the
"
"
of each minute.
end
587.
For what
purpose
is a local
588.
For what
purpose
is
589.
What
is
in in
car-brake? electro-magnetic
an
attraction between an
a
batteryused used local battery
the wheel
in which
One
the brake
and
telephony? ? telegraphy
is
netic mag-
employed to stop
electric car. of air. dependent on the expansibility 591. Devise a thermostat dependent on the dilation of a metal. 592. What is an ordinaryelectric bell ? Merely a vibratingcontact-breaker 590.
Devise
a
thermostat
carryinga
small
hammer
which
strikes
bell.
a
magnetic bell? It is a bell intended to be used with a small magneto-dynamo which furnishes an alternating current. 594. What is a buzzer,and how is it constructed ? 595. What do you understand by electrical storageof energy "? 593.
What
is
a
"
596. used
What
is
converter
a
to transform
a
current
or
of
transformer?
It is
into high intensity
a
an
instrument
current
of low
intensity. 597. How coils.
That
is it constructed? which
It is
correspondsto the
virtuallya pair of induction core
is
a
mass
of laminated
iron.
byGoogk
Digitized
40
EXERCISES
ooil of
is it used?
How
608.
IK
The
PHYSICS.
indadng
the induced
and high resistance,
is sent
cmrent
corrents
tfaronghthe
generatedin the
aie
low-resistancecoiL 500.
What
machine
and
gain in
analogy is there between
from
What
"
a
high
of
converted 001.
you may with a oon-
vice versoj so or you lose in velocityy gain in E.M.F. what you lose in current, or vice
Describe
currents
ordinary
an
the former
with
force what
yerter you may
600.
electrical converter?
an
the functions of As
converter
E.M.F.
and
and
the
by which
method of low
strong currents
vena.
weak
"Jtf.F. may
be
into the other.
one
Foucault
are
"
circuitsof small resistance
?
currents
Local currents
by variations
set up in closed
in the electric currents
flowing of these circuits through magnetic near them, or by the movement hence a great and pole pieces, fields, causinga heatingof armatures of energy. is done to reduce 602. What
waste
armature
cores
603. How
is a laminated
anglesto the direction
by
What
Pole
piecesand
another
one
in which
and
Usuallyof a pileof sheets placed in planes at right
the Foucault
galvanometerby
would
currents
is wire in resistance coils doubled
Why
openingand 605.
made?
core
the disturbance of the on
currents?
laminated.
are
of iron insulated from
604.
Foucault
on
extra
move.
itself?
currents
To
vent pre-
generated
closingthe circuit. is Lenz's law?
The
induction electro-magnetic
direction of the currents
always
tends
to
A
current
which
strengthof
current
produced
the
oppose
moticm
producingthem. 606. What made
direct
607.
is ""
or
What
a
"
one-way
is current
by
it
609. Does becomes
a
The
current
per square
flowing out of
a
batteryand
misleading?
it not
suggest the rather pertinentquestion,'"What
when electricity
610.
When
would
you wind
611.
When
would
612.
Under
what
you use a circumstances
613.
been
commutator.
of the
nometer
has
conductor.
a
Is not the idea of
returningto
a
density?
inch of the cross-section of 608.
current?
commuted
it gets back ?
"
with fine wire electro-magnet short-coil galvanometer?
an
is it necessary
to
employ
a
?
g^va-
of small resistance ? What
does
absolute
calibration
of
a
galvanometer
mean?
byGoogk
Digitized
41
ELECTRICITY.
Marking
614. How
should
thermo-electric
not
galvanometershave in
into
a
=
of wire
thirtyturns
to
to suit 1""* in
ohm. and electro-magnets
; in which
r
of naked
diameter
effect?
The
best
resistance of coil,
=
wire,a
+ (
diameter
=
covering. currents
extra
can
be
nearly abolished?
By doubling
itself.
on
617.
"^"-
-^ =
616. How wire
strengthsin
galvanometer be wound
order to obtain the maximum
a resistance,
external
of wire with
a
Twenty
exceedingi
produced when
effect is
a
thickness of wire should the coils of
What
615.
the coils of
currents?
diameter, resistance
=
the current
correspondingto each deflection.
amperes
R
the instrument
graduationof
the
or
How
extra
can
be intensified ?
currents
and stillmore close coil,
By winding the wire
by puttinga pieceof
iron inside the coil.
greateffect does the mtroduction of an iron core into a helix produce ? It makes the internal magnetic field about 33 times intense. more Wigan. is the specific office of a dynamo ? To develop differ619. What ence 618.
How
"
of 620.
potential. What
dynamo and and
illustration of the reciprocal action of a simplest electric motor? The original Bell telephonetransmitter is the
receiver. 621.
What
are
622.
What
should be their
623.
What
coils of
a
? polepieces
is the
dynamo ?
shape?
proper resistance to be For series
dynamos
given the field-magnet
the resistance should
be less
than that of the armature. 624.
What
is the officeof
625.
What
is
a
Why are prevent heatingand 627. Where 628. Is
a
conmiutator
?
selfnexciting dynamo?
brushes
626.
a
dynamos generallymade
on
corrosion
should brushes
of
To
copper?
by sparking. touch
armature high-resistance
a
commutator
necessary for
ring? high E.M.F.
in
a
dynamo? 629. German 630.
If
high resistance
in the armature
were
requisite, might
silver wire be substituted for copper wire? What is the relation of speed to the E.M.F.
within directly proportional
certain limits
not
generated? It
(except in series
or
shunt
byGoogk
Digitized
is
42
PHYSICS.
IN
EXERCISES
dynamos), provided resistance of the external circuit remains of the author's
The armatore
631. a
resistance of 0.6 ohm
a
resistance of 9.3 ohms.
lamp which accompaniesit has Assuming that when the lamp is introduced
would
?
Zero.
636.
On
in
arc
or
in series?
the essentials of
together;long
near
good
a
and
thick
what
;
does the action of all
pend? practicalelectric motors deattractions and On magnetic repulsions. Two magneto-dynamos or two series dynamos are connected
wires.
of them 638.
into the circuit,which
connected
and
dynamo
greatspeed of rotation. Which of the above requirementsare incompatible? is the current of a dynamo at the instant of commutaWhat tion
635.
by
when results,
Strong field magnets
the armature
634.
637.
introduced
were
the
will be maintained?
current
What" theoretically q"ea]dng,are
dynamo? on
lamps
better
produce the
633.
wire
such
If two
632.
resistance appreciable
no
of 8 Yolts,what
E.M.F.
an
hand-powermagneto-dynamo has
; the incandescent
into circuit by short,stout wires of furnishes
stant. con-
Describe in full what
is rotated What
is a
will
when
occur
the armature
of
one
by mechanical power. machine? dynamo-electric
drawing of some simple arrangement which will illustrate the principles of a dynamo. 640. Is the dynamo employed for generatingelectric currents for telegraphing? In Chicago,dynamos have entirelysuperseded the 639. Make
a
gravitybatteries. What
A pieceof magnetized steel polarizedarmature? placednear the polesof an electro-magnet A current passed through according the coils of the electro-magnet attraction or repulsion, causes the adjacentpoleshave the same as or oppositepolarity;e.g, the armature in telephonecall-beUs. 642. How much energy is a six-horse-power electric motor capable
641.
of
is
expendingin 643. What
dynamo?
A
an
hour?
kind
of
how resistance,
as
will
is used
armature
bipolardrum
644. Inasmuch
645.
a
magneto-
armature.
fieldmagnets cannot some
in the author's
energy
be constructed without
some
be wasted ?
Specifyexperimentswhich
can
be
performed only with
a
way one-
current.
byGoogk
Digitized
43
MAGNETISM.
646.
is the commercial
What
of a dynamo efficiency
?
The
ratio
of the available energy in the external part of the circuit to the total the dynamo. energy expended in operating 647.
is it
Why
the handles
difficult to turn
of
a
magneto-
it is broken ?
the circuit is closed than when
dynamo when
generated by an alternating-current dynamo Yes, on certain througha similar dynamo drive it as a motor?
648. Can sent
more
a
current
conditions. 649.
Specifyuses
650.
Show
that
651.
What
must
which a
may
be made
of
an
current. alternating
telephonereceiver is an electric motor. be the voltagein order that a current of
may have the power of 5 watts ? 652. What has been achieved success
0.2
pere am-
in the line of electricwelding?
brass, and Wrought-iron,cast-iron,
diameter,to
the smallest
wires used
copper rods from 2 J in. for electrical conductors, lar dissimi-
metals,and the ends of wire cables may be welded together.
MAGNETISM. 653. to be
an
654.
from
magnetism? It is thought by many close thinkers in a state of rotation. electric whirl," or electricity Do the hypothetical ampere-currentsflow around the earth
What
is
"
east to
west, or from
655.
Is the Arctic
656.
Can
breakingthe 657.
What
658.
What
659.
Show
west
to east ?
magnetic pole of the earth positiveor negative? from its S-poleby a N-pole of a magnet be separated magnet? do you understand by the Jieldof a magnet? is the officeof the Jieldmagnet of a dynamo ? that the directive force which
the e^*th
exerts
upon
a
magnetic needle is a mechanical couple. 660. Why to the pole of a do we apply the term north-seeking magnet which pointsto the north magneticpole of the earth ? 661. What is meant by sayingthat the magneticdip at London in 67" 30'? the year 1889 was 662. Suppose two magneticneedles to be
suspended at their centers
by silk fibers,one in Boston and the other in Chicago,how could of the magneticnorth pole of the earth be discovered? position
the
byGoogk
Digitized
44
EXERCISES
663.
What
IN
PHYSICS.
is the
meaning of the eaEpreeaioiia "geognqahicalmeridian** and ^'magnetic meridian"? What is given to the an^ name the two
between
What
664.
meridians?
caoses
a
magnetic needle
to take
a
positionnorth and
south? The
665.
OJT^.
declination of the
magnetic needle in Boston
in 1782
was
centurylater it was 11.7^. What does this show? 666. Which is more probable,that the earth is of the nature of a permanent magnet, or that it is in the condition of a solenoid? 667. The magnetic dip of Boston is 74^. What is meant by this A
statement? There
668.
is no
evidence to show
that the American
pole of vertichanged since its discoveryby Captain Boss; on cityhas perceptibly the other hand the (Asiatic) Siberian pole has of late years been moving Can Stewart. in eastward. discover this Balfour you any reason that it is under the influence of both mi^netic why, on the supposition time, systems,the western declination of the needle in London has,meanbeen increasing? 669. Why will a horizontal needle stand in any position at a magnetic "
poleof 670. What
the earth? is the
magnitude of
the horizontal force at
a
magnetic
pole of the earth? 671. With caUed
**
what
polesof
are propriety verticity?
the
magnetic poles of the earth
"
672. Towards
what
lines converge? pointsdo isogonic the two foci of maximum 673. Where are magnetic force? 674. State several facts concerninga magneticpole of the earth. 675. Take a Tcaap of the United States,and with a pencil draw line of no declination) for from the data given the agonic line (t.". the year 1890. Start at Charleston, S.C., and draw consecutively Lat. 81 Lon. Lat. the 35, 40, L"m. 83 ; followingpoints: ; through Lat 43, L"m. 84; Lat. 47, Lon. 86.
676. What on
its
is meant
by the
horizontal
of magneticintensity
a
place
the earth? 677.
What
is meant
678.
What
is meant
679.
Draw
a
of by the vertical intensity by "the total force"?
the diagram illustrating
a
place?
relation of the total force to
components. 680.
What
is
a
magnetic screen?
A
receptaclehaving thick
byGoogk
Digitized
46
EXERCISES
variation of
watches),a
j^
part of
seconds per
695. What
causes principal
in
well-";onstructed watch?
a
vibration
a
day ?
variation of how
many the are
PHYSICS.
IN
would
that tend to
Variation of
producevariations
temperature;rust
hair-spring ; variation of elasticforce of the
or
atmosphericpressure ; magnetic influences of steel. How
696.
?
It
does
causes
a a
Ichangeof temperature affect
variation of distance between
the center of oscillation of the
and
in the elasticforce of the
A watch
699.
What
State
a
magnet
parts ment move-
pointof support a
variation
hair-spring. onlyis the compensating
?
method
some
be secured.
by
which
Place the watch
substance para-magnetic
some
the
on
broughtinto the fieldof a strongmagnet stops; why ? permanent injuryis sure to ensue if a watch is brought
into the fieldof
may
hair-spring ;
calculated to correct ?
698.
700.
the
ance-whee bal-
on
the rate of
balance-wheel,and
697. .Which of the tendencies to variation balance-wheel
a
90.
variations of made
occasion
in
efficient protection tolerably a
shield-box
case
or
made
of
; e.g. iron.
of appears at presentto be the most efficient means ? Substitute for steel some overcomingthis difficulty ble non-magnetiza701.
What
material that possesses all the virtues of steel. these 702. Is there any material which answers Yes ; certain
alloysof
palladiumare
almost
requirements?
completelynon-magnetizable,
ductile,and non-dilatable, unoxidizable, Of what
703.
does this
alloyconsist?
highlyelastic. of palladium, Chiefly copper,
and iron. to affect alloyingof these substances seem their magnetic properties?Their magnetic properties to be seem masked one by another. is a veritable 705. What does this fact possibly argue ? That an alloy chemical compound. 704.
does the
How
HEAT. 706.
In
described views
now
Physicswritten in the year 1800 latent heat is firewhich has lost its faculty of heating."Contrast the as entertained of this subject with those of the epoch named. a
work
on
*'
byGoogk
Digitized
47
HEAT.
707. Which, force
or
energy,
708.
Are
molecules
supposedto
709.
Are
the terms
heat and
into heat?
be transformed
can
be elastic?
cold
of
names
only of different degreesof the 710. Why is chemical combination or
same
ent, differthingsessentially
thing?
attended
by
a
generationof
heat? 711.
To what
are
the heat and
lightof
meteoric
stones
due ?
To
of kinetic mass-energy into heat by the friction of to the destruction of the body'svelocity.
the transformation the air ;
%,e,
the sides of
do the
impact of the molecules of a gas on the containingvessel giverise to a constant pressure? 712.
How
713.
What
714.
The
is the total pressure of several mixed gases equal to ? pressures exerted by saturated vapors of water, as found
follows: as temperatures are respectively 20" C, 17.4""; 30", 31.6""; 40", 55""";50",92""; 60",149""; 70", 232""; 80",863""" ; 90",566""" ; 100",760""". Draw a pressure curve, and pressures by ordinates. temperature by abscissas, repiesenting [SeeTechnics, page 1.] 715. Confine a body of air in a vessel havingrigidsides,and lower How tiie temperature of the air; will the air contract? are gases
by Regnault,at
affected 716.
by
different
reduction of
What
temperature? is the cause of gases exertingpressure?
Upon what does the quantityof pressure exerted by a given gas depend? 718. Accordingto the law of Avogadro,equal volumes of different 717.
temperaturecontain the same gases at the same Would the average velocities of the molecules the same under these conditions ? 719. same
as
Show
that if a
that of
a
body of
of the former 720.
On
temperatureof
what
must
a
number
of molecules.
in different gases be
body of hydrogen gas
is the
of the molecules oxygen gas, the average velocity be four times that of the latter.
does that condition of
a
body
called its
temperature
depend? 721. colder
Does
a
hotter
contain body necessarily
heat
more
than
body?
722.
Wliat is absolute
728.
What
724.
How
much
warmer
726.
How
much
colder is 0" F. than 0" C. ?
or
is increase of
thermo-dynamictemperature? due to? temperaturedirectly is 0" C. than the absolute zero?
byGoogk
Digitized
a
48
EXERCISES
much
colder is -10"" F. ihan lO^ F. ?
726.
How
727.
Sulphuricacid
is susceptible of
temperatureof to what ? proportional The
What
being how
much
colder than
C?
its freezingpoint,-44^ 728.
PHYSICS.
IK
body reckoned
a
from
absolute
an
zero
is
is the absolute
temperatureof boilingwater? 730. The English standard yard is representedby two lines drawn
729.
goldstuds being62^ F.
two
across
0.00000947
for 1^
lines would
two
0.000341
in
The
F.,what
bronze
bar about 38 in. long,the temperature
coefficient of
expansion of bronze
difference in the distance of
change
a
a
temperature of
732.
What
733.
What
is the lowest
temperaturethat
will you imponderable fluid?
heat is an 734. If
make?
have ?
body can
a
body of
a
? Would
give for rejectingthe
reason
gas at 0^ C.
and its temperaturewere
lowered
it cease
to diminish
Which
736.
Find
is the
If so, how
on
body
may
theorythat
rigidhollow shell,
a
much
?
ish dimin-
If its pressure
rate, at what
same
temperature
? theoretically
highertemperature, 20"
the number
old
a
degree,would its volume
one
at the
to exert pressure
735.
inclosed in
were
its pressure diminish ?
to continue
would
these
d^ree
one
is your conceptionof that state in which be said to have no heat?
were
being
between
in. What
731.
sunk
Fahrenheit
a
C.
or
68" F. ?
thermometer
ing correspond-
C. ?
to -12"
temperatureof melting ice ? 738. Whatrangeof temperaturemay ice haye? What
737.
739. What What
for its
zero
the
of freezing-point
is the
heat?
no
740. that has 741. above
has
thermometer
mometer, temperature,according to a Fahrenheit therof meltingice? What is the temperature of a body that
water?
has
is the absolute
an
Express in no
centigradereadingthe temperature of
a
a
body
heat.
The
of tCTiperature
absolute
zero.
a
What
certain
room
is 300
temperature would
centigradedegrees thermometer a centigrade
indicate if placedin the room? 742. What
was
the
scope),and by whom about the year 1597.
(more properlythermoair-thermometer, by Gralileo,
originalthermometer
constructed?
An -
^
byGoogk
Digitized
49
HEAT.
743. When Where
744.
Fahrenheit
did
his residence ?
was
In 1714.
Dantzig.
thermometer
is the standard
745. What
his thermometer?
construct
for scientific
purposes?
air-thermometer.
The
746. tedious 747.
Why is it not more generallyused ? computations. bore employed in Why is a capillary
748.
is it
Why
thermometer 749*
the stem
of
Would
thermometer
a
changes of temperatureas quicklyas is the most
What
involves
use
a
ter? thermome-
of radiant energy ?
one
The
a
thermometer
having a large bulb having a small bulb
sensitive instrument
a
?
diameter
effect has the size of the bulb of
What
sensitiveness?
750.
its
highly important that the bore of the tube in
should be of uniform
stem
Because
on
its
indicate ?
for
measuring intensity invented by Professor Langley.
bolometer
751. Is it
to have a little air in the stem of a thermometer? objectionable No; it is rather desirable,as it will prevent the mercury it is used in a horizontal or from flowingthrough the stem when inverted position.
752.
What
does the air sometimes
annoyance
the mercury as during transportation, violently, small
How
the
may hand the bringing
the
feet 754.
holds it down
same
If the
top of
a
the column
Did
Fahrenheit
brought together? Easily,by ing rapidly,and suddenly arrest-
principleas
thermometer of mercury ? select for a
What
did Celsius,in
select for 757.
a
When
C, you
zero
?
you
state that
that
mean
What
do you is 68" F. ? Do scale has 758.
remove
snow
or
mud
from
Which
when
mean
over
the centigradethermometer, constructing
the
say
discover fvom
you
be
(i.e,a pointfrom which to natural which any particular
temperature of
its temperature is 20" you
off,what would
knocked
zero
temperature) a temperature at phenomenon occurs? 756.
we
were
reckon
one
get separatedby
may
by kicking a door-rock,
the effect on 755.
be
mercury
which
its motion, on
20"
If shaken
cushions of air.
753.
our
occasion ?
a
certain
that the temperature of
these
what?
than
warmer
is
room
a
room
questionsany advantage that
the other ?
will
answer
better for
alcohol an high temperatures,
byGoogk
Digitized
or
50
EXERCISES
meiciiry thermometer? tremelylow temperatures? What
Idnd of
regionsneed? perature?
Would
What
760. can
Would
be reduced
761. How
a
thermometer
a
will
better for
answer
ex*
Why ?
such
would
thermometer
a
only way
below
that of
by
traveler in the Arctic
a
fail to indicate tenn-
eyer
thermometer
mercury
is the
can
PHYSICS.
Which
Why?
a
750.
IN
which
ever
fail to indicate
the
temperature of
ature? temper-
body
a
surrounding bodies ?
the latent heat of water
be transformed
into sensible
heat?
sion? 763.
is the
How
762.
Why? Through
temperat^nreof air affected by sudden
what
range
of
temperature
water
may
conqnresexist in
a
solid state? 764. If you allow water "8^ C, what effect will it
to freeze in
produce
on
whose
temperature is the temperature of the room? a
room
Explain. .
can
765.
liter of water
A
at 20^
C. must
lose how
much
heat before
it
freeze? 766.
Explain fuUy
767.
Find the difference between
of water
the effect of pressure
at 20^ C. must
heat which
the
lose before it
it loses while
can
used
quantityof
in
heat which
freeze and
i.e.while freezing,
making
the
balls. snow-
a
liter
quantityof
its temperature remains
constant.
through water it must be stirred. Why? Show how it may be self-stirring. of a liquid, where must the heat 769. In testingthe conductivity be applied? Why? ftam the 770. Is the temperature of the atmosf^re uniform ground upward? It diminishes at the rate of about 1^ C. for every 768.
To
diffuse heat
162 meters.
771.
Why
land-breezes
have generally during the night? do
we
seabreezes
during the day
and
ment), heatingapparatusconsists of a boiler (in the basefrom the top of which pipeslead up through the rooms above, Boiler and pipes are and return to the lower part of the boiler. How is heat distributed through the constantlyfilled with water. 772.
Hot
water
house?
Digitized by
61
HEAT.
773.
When
heat does
work, does it disappearas heat? extremelylow temperaturesbe obtained
774.
Why must processes?
775. Define the different units of heat in
The
use.
by
ficial arti-
calorie is the
requiredto raise 1^ of water from 0" to 1" C. ; the lesser calorie is the quantity of heat requiredto raise Ik of water from 0" to 1^ C. ; and the mechanical unit,which is the quantityof heat equivalentto one erg. A calorie is equivalentto about 41,595,-
quantityof
heat
000,000 mechanical
units.
776. Mix, in suitable 32"
the
F., and
temperature of the mixture
Explain. in 777. By dissolving the water, the water 778. What mixture?
rock proportions,
ice at
will fall to about
certain solids which
water
is made
salt at 60" F. with
0" F.
than
warmer
are
colder.
is the lowest
Explain. temperature attainable with
a
salt-iee
-12"F.
779. Ice melts
and
water
freezes at the
same
temperature; what
thingswill happen in any case ? 780. A man ascending a stair is found (Him) to be perceptibly cooler for a moment, althoughthe exercise, circulation, by stimulating him to become warmer come causes immediatelyafter. Why does he bedetermines
which
of these two
cooler? 781.
The
most
artificial means
efficientmethod
of
temperature by is by the evaporation of liquids. What kind of
obtaininga
low
that would some liquidswould be selected for the purpose ? Name be especially suitable. 782. How is ice usuallymanufactured Cans containing artificially? distilledwater
suspendedin brine. The brine is reduced to a temperaturebelow the freezing-point of fresh water by having submerged in it metal pipes throughwhich liquidammonia is allowed
to
783. How
to be frozen
are
expand into is the
a gas. reduction of
temperature in this operation
explained? 784. At what
temperaturedoes ammonia
boil?
785. It sometimes the
of vicinity
happensthat in the springwhen water-pipesbegins to thaw, the water
beginsto freeze. Explain. 786. Why is there an increased sensation ? graspingthe bulb of a pulse-glass
C.
"34"
the
of cold for
in
ground in the pipes
a
time
byGoogk
Digitized
after
62
EXEBCISS8
In
787.
ft
water
Tieanniy
IK
FHTBICS.
be irooen
may
hj
its
Why is the operationof fanning one's self doobtfnl expediency? 789. Why is water better than any other liqnidto hot water heatingapparatuses? modem 788.
What
790.
is
name
giTen
to
a
sobstanoe
eraponftion.
own
keep cool of
to
be nsed
in
which, mixed
oar
with
another,renders the latter fnable? 791. What
weightof weightof
What
792.
ioe will 10^ of water
at 9(F C. melt?
ioe wiU
at 100"
10^ of steam
C. melt?
weighing 10^ is moying with a yelodtyof 200^ per What is the thermal equiralentof its energy ? second. 794. The molecnlar work done in melting 1^ of ice is equiyalent ball
A
793.
to how
mncfa mechanical
work?
converting1^ of water into steam under atmos^iericpressure is how great? average 796. How are extremelylow temperatures,such as are necessary to liquefyoxygen, obteined ? 797. Why does cold water in the palm of the hand become warm, 795.
The
work
done
in
while cold ether becomes 798. shown
The
colder?
of nitrous boiling-point
that the
temperatureof
oxide is "88"
C.
Bontigny has in the spheroidalstate poured into a red-hot
liqnidwhen ite boiling-point. If this liquidwere and ite vessel, floated on a capsulecontainingwater or mercury were surface,what would happen to the liquidin the capsule? 799. What is understood by the "critical temperature" of a liquid? Above this temperatureis it probablethat a substance can exist in a liquidstete? 800. When, accordingto the kinetic theory of gases, is a space a
is below
saturated 801.
what
a
1^
will be the
802. what
with Pour
Mix
vapor? of water
at 100" C. upon
1^ of ice
chips at
-10"
C;
resulting temperature?
1 lb. of water
at 150" F. with
10 lbs. of water
at 140" F. ;
will be the
803.
temperatureof the mixture? Explain the following equation : Water
at 0"
=
ice at
0" +
latent heat. 804.
Transpose the
atO"; also 805.
of
Write
above equation and determine latent heat. an
equation for
steam
the value of ice
at 100".
byGoogk
Digitized
54
SXEBCI8E8
temperatuieabove which 828.
On what
829.
What
pressaie of 830. What
PHYBICS.
is the critical temperature of
827. What
a
IN
the substance
snbstanoe?
a
exist in
cannot
a
It
is
a
liquidstate.
is the criticalstate
dependent? On largely is a criticaltemperatureof hydrogen? "174^ 99 atmospheres. AntMany and BrackeU.
piessnre.
C. nnder
"
is
criticaltemperatuieof oxygen
a
?
"105^
nnder
42
nnder
42
atmospheres. What
831.
is
a
criticaltemperatnreof
nitrogen? "124^
atmospheres. the steam
Has
832.
the
same
perature tem-
the brine ?
as
Why,
833.
arisingfrom boilingsalt water
in
of a thermometer,is not the fixingthe boiling-point
bnib allowed to be in the 834.
What
835.
How
water? boiling
is the absolute temperatuie at which
hydrogen boils? do substances in solution^less volatile than the solvent,
? aifect its boiling-point
If
836.
body of
certain
at 20^ C. exert
pressure of 10 lbs. perature per square inch, what pressure per square inch will it exert if its temis raised to 100^ C. and it is not allowed to expand? a
837. 500^
of air
expand
gas
to 750^
without
a
change of temperature;
a
what
exert? part of its original pressure per square inch does it now 838. Suppose that a body of air whose Yolume is 500^ and tentperatureis 15^ C. exerts a pressure of IC per square centimeter,what pressure will it exert if its temperature is raised to 250" C. and its
becomes
volume
The
839.
?
560^
vapor
of nitrous oxide
gas
at
pressure of 30 atmospheres; what ? reference to its boiling-point exerts
a
a
temperature of
does
QP
C.
this indicate with
that as body whose temperature is the same ? work of surroundingbodies available for doing that in order to get work from heat there must 841. Show be of temperature. inequality tudes 842. What is a hypsometer? An instrument for determiningalti840. Is the heat of
by
of the
means
what
843. On
temperatureof
can
the
845. How
can
water
the crank
In
a
in
of water. boiling-points
condition does water
844^ How
846.
a
be made
boil at 100"^ C.
water
or
212" F. ?
be raised to 200" C. ?
to boil at 100" F.?
steam-enginethe piston travels four times the lengthof revolution. If the crank whose lengthis 9 ft. makes one
byGoogk
Digitized
55
SOUND.
70 revolutions per minute, the area of the pistonis 150 sq. in.,and the pressure of the steam on the pistonis 60 lbs. per average unbalanced of work done per minute ? what is the quantity sq. in., is the h. p. of the
847. What 848. How
can
of cloth be
web
a
engine? from
woven
delicate and
brittle
and imsteady force generated in a (say) by the tremendous 50 h. p. engine? checked when 849. Why is not the speed of machinery sensibly great resistances are encountered, such as in planing and boring
threads
iron? 850.
engine,the tension.
steam
on
is the difference of tension secured ?
How
851. What 852.
of a steammay do work in the cylinder oppositesides of the piston must have different
In order that steam
is destructive distillation? is fractional distillation?
What
of ice lowered for each additional melting-point of a degree Fahrenheit. atmosphericpressure ? One seventy-fifth
853.
"
How
much
is the
Maxwell,
is meant
854. What
by
the
phrase latent
heat
effusion?
SOUND. 855.
State how
differfrom
one
motions
of rotation,translation, and
another, and show
that the matter
undulation
composing the earth
has all these motions. 856.
How
water-wave
do the
series of concentric
at
above exist in
a
in amplitudesof the vibrations of the particles
a
named
What
waves
compare
is the technical
?
Why
?
given to imaginarystraightlines
name
rightauglesto a wave-front or a series of wave-fronts ? 859. In stationary vibrations what distance expressed in are
the nodal
one
thingsdoes the
the rate at which
they travel and
On
what
pointsfrom
two
860.
On
of the motions
?
857. How
858.
which
and
many
lengths wave-
another ?
lengthof sound-waves on
depend?
the vibration rate of their
source.
861.
On
what
does
the
velocitywith
which
sound-waves
travel
byGoogk
Digitized
56
EXERCISES
depead ?
It varieB
the medium
absolute 863.
PHYSICS.
the square root of the ratio of the
as
of elasticity
to its density.
862. Would an
IN
A
Tibraie unyisoous tuning-fork absolutely
an
waye^ength is
the distance traversed
by
a
864.
Explain
energy lost" 865. What
how
''the
noise
of
is the distance between
similar
moving machineiy represents any
pointin its predecessor or
pointin
a
and
wave
If the energy of a wave is lost as it advances, what the vibration of the particles ? will occur 867.
A
rod free at both
tube. open located? 868.
How
What
many
is understood
produced,for example, on 869. What advantagefor vibrations to middle octaves
ends vibrates like
nodes
are
has
and
the
The
sound
takes
change
of air in
column
where
in
an
they
are
composite sound, such
a
scientific purposes
C ?
The
vibration
is there in
numbers
assigning
of the
sive succes-
of 2.
propertiesof
a
propertiesof
a
sound-wave
that
sity, sound-sensation,viz. pitch,inten-
quality.
871. How 872.
cisely pre-
stringedinstrument?
a
exact
the three
a
rod, and
by the pitchof
powers 870. State respectively the three determine
the
a
called?
successor
866.
256
in
wave
time?
what
as
in
?
vacuum
sound
iGwrer
is pitchaffected
by loadinga vibratingbody
periodof vibration in how
to travel
many
?
open organ-pipeis the time it times back and forth the length of an
pipe? 873.
which
How
does the
temperatureof the
air affect the
with velocity
it transmits sound-waves?
874.
Why
should
catgut stringgive a higher note than a wire of the same lengthand size? 875. Why fired on does a cannon a mountain-topproduce a
steel
paratively com-
littlesound? 876. A
certain
soimdingbody becomes
inaudible
at
a
distance of
pare the ear, and another body at a distance of 500 ft. Comthe intensities of the sound-waves eminatingfrom the two bodies.
100 ft. from
byGoogk
Digitized
BADIANT
57
ENEB6Y.
RADIANT
ENERGY.
of ether? anything of the properties of its existence, there are many Once hayingacceptedthe hypothesis and otherwise)of determining its properties by ways (experimental which associated. with it is the phenomena 878. What, accordingto Sir William Thomson, are atoms of in the all-pervading imbedded matter? ""Not foreignparticles ether, it of differentiated off from the of vortex rest but portions by reason 877. How
can
know
we
frigidspecks,but each composed of whirlingether." 879. What of matis the popular theoryconcerning the essence ter? "" it That is rotating vortex motion of an portionsof ether,ue, everywherepresentfluid." 880. What is a tion. perfectfluid ? One in which there is no fric-
motion
; not hard
"
'"
Is there
881.
perfectfluid?
a
Yes; all space is supposed to be
fiUed with it 882. If
a
vortex
motion
were
started in
perfectfluid,would it
a
cease?
ever
What
883.
is the
earth's surface?
densityof
It is
the
atmosphere4000 expressedby a number with
miles
above
the
ciphersafter the decimal pointbefore the significant figuresbegin." Lodge, is the density 884. What of the ether? It is expressedby a decimal fraction with 17 ciphersbefore the significant figures. Sir Wm, ""
127 "
"
Thomson. 885.
Is
force great? gravitation
Ask
yourselfwhether
of lead attract each other with much
masses
886.
two
pound-
force.
To what
conceptionof the material universe does Thomson's geneous homotheorylead? That it is one universal substance,perfectly and continuous in structure, extending to the furthest limits of space, certain districts of which contain whirling portions called and not by matter, capable of transmittingenergy by continuity, impact. is the Maxwellian 887. What tion theoryof light? That it is a sensa-
producedby
electricalvibration of ether ;
ue,
that its
waves
are
electricalwaves. 888. What
is there justification
and electricwaves
for the
appear to be transverse
theory?
Both
light-waves vibrations traveling through
byGoogk
Digitized
58
IN
15XEBGISES
PHYSICS.
ether ; the velocity of both are the same ; the speed of both vary with the media ; the index of refraction is generally the geometric mean of
capacities. magnetic specific
its electrostaticand To
880.
produceether-wayes
meter
a
in
lengthrequires300,000,000 are required
vibrations per second ; hoyr many vibrations per second of the same to produce sound-waves length? What
890.
are
to call those short ethereal
accustomed
we
waves
affect the retina ?
which
of ethereal waves, radiations, or peculiarity haps (perwaves, better)pulses? They are not end-thrust pulses,like soundbut they have a lateral propulsion as .bya series of rotating
891.
What
wheels whose 892. can
is the
axes
Why
can
lie in the direction of the motion
weigh air,but
we
not ether ?
of translation.
Because
the former
while the latter cannot. compressed and rarefied, 893. What is ether supposed to be ? A continuous (hence sometimes called solid "), incompressible, vacuum-less,perinexpansible, fect be
'*
fluid. 894.
What
is the function
What
is meant
of ether?
To
transmit
motion
and
energy. 895.
Resistance to 896. not
it is said that ether possesses
i.e.to shearingstress,
Why
is ether said to be
molecular,and 897.
when
Does
"*
alteration in
solid
"
?
? rigidity
shape.
Because
it is continuous,
rigidity.
possesses
ether transmit
radiant
heat
without
itself
becoming
heated? 898.
Is ether which
899.
With
fillsall space
or
cold ?
and its phenomena more
is lightmost electricity, closelyallied, nearlyanalogous? Electricity. The whole
domain
annexed
900.
Which
of
which, sound
warm
Opticsis now
What
"*
would
name
is smaller,atoms
or
or
be
method
a
902.
State
of the most
903.
When
a
by
which
has
fluid which
light-waves?Atoms
Is radiation
storingup the
Electricity."
given to
901.
some
to
much
are
no
viscosity? smaller.
heat travels?
importanttraps
for
retainingand
sun's radiant energy which the earth receives. ? When is radiant heat light its frequencyof vibration
904.
400 million millions and 800 million millions per second. At what temperaturewould a body cease to radiate heat?
905.
Explain the so-called
906.
A square
is between
meter
Theory of Exchanges." to the of surface exposed perpendicularly "*
sun's
byGoogk
Digitized
BADIANT
rays receives from the sun of heat were this quantity
59
ENERGY.
each minute
about 25 calories of heat.
transformed
without
If
loss into mechanical
of work per hour? energy, it would be capableof doing what amount 907. A horse-poweris equivalentto about 2.7 calories per minute. Each
meter
square
of
when surface,
the
sun
is directly overhead,would
continuously? many horse-powers Give illustrations of the transformation
receive how 908.
ether-waves 909.
into molecular
How
On space ? receives? 910. Are
do
912.
second?
many
How
many 5x10".
913.
How
914.
Translate
heat,"into of the subject.
.
exchange heat across an intervening will a body impart more than it
?
vibration
periodshas hydrogen? Three.
vibrations does
an
of sodium
atom
make
in
a
lightthe earth? the expressionused by Tyndalland others, dark language in harmony with our presentconceptions
does the
radiant
of
the or heat, light,and actinism the properties
radiant
of radiation effects 911. How
condition
what
energy
work.
bodies
two
of the
sun
and
warm
"
915. Is there any difference between a heat-ray and a light-ray? 916. What transformations of energy occur in a radiometer ? do the phenomena exhibited by the radiometer afford 917. How
strongexperimentalconfirmaticm of the kinetic theoryof gases? 918. The palm of the hand held near the bulb of a radiometer will cause
its vanes
vanes
onlyradiant
919. How
to revolve.
by
Show
"
transmit
to the
candle,Bunthe greatestdistances that each will produce can
energy of the several flames ? does it appear that 920. How
our
modes
temperatureat which
the lower vibrations into
"
e.g,
cal the relative mechani-
you compare
wasteful? are artificially exceedingly the
can
energy. placingflames of different kinds
etc. at spirit, motion in a givenradiometer sen,
that the hand
of
manufacturing lightwaves
In
the matter to raising do not transmute we light-waves, but simplysuperpose the higherupon higher, it emits
the lower ; hence the lower vibrations are wasted. order to sound some littleshrill octave of pipesin an
organ,
obligedto depressevery key and pedal,and
a
"It is as
to blow
young
we
if,in were
hurri-
byGoogk
Digitized
60
SXERGISES
921.
What
animal
when
does
Why
looked at
923. What
may
brightwall
a
through a
narrow
should be the
illuminate at
to
produce light-waves
bright at all distances appear equally tube ?
of candle-power
distance of 5 ft. a
a
PHYSICS.
yet teach us how of energy ? The glow-worm.
with littlewaste 022.
IN
gas-burnerthat it may
a
printed page
as
as brightly
a
candle
at the distance of 1 ft. ?
When
924.
the
about 60,000times
What
meters.
925. Will hot stove?
marked, 927.
ablaze. 928.
from
sun
is the sim's
a
standard candle
the earth
is "
candle-power
*'
glass mirror
a
at
a a
white
surface
distance of 1".
(roughly)150,000 million ?
well to reflect radiations from
answer
a
Why?
Why
926.
as strongly
as
distance of the
The
is in the zeniti^, it illuminates
sun
shadows
are
i,e, so free from
Distant
cast
by
the
electric
arc-lamp so
sharply
penumbra?
windows
often appear
just before
to be
sunset
all
Explain. do
Why
observe
we
this
phenon^enon only when
the
sun
is
the horizon ?
near
929.
The
electric
the light,especially
when arc-light,
viewed
through a Bunsen flame that has been made yellowwith salt,has a bluish tinge. Explain. 930. Is a perfectly transparentbody visible? but is quite 931. A solution of alum transmits short ether-waves, ? Is it transparent?diathermanous imperviousto long waves. 932. Why is the intensity of sunlightat noon greaterthan during earlier or later portions of the 933.
Why
and red when 934.
Place
a
The
exposed to
white
waves, light-
? light-waves
uprightin sunlight.When
its shadow
est is short-
meridian ?
moon
which climate,etc.,
a
exposed to red
stick
it lies in what 935.
day?
is pulverized glasswhite when
is an
airlessplanet; state difiEerencesin
planetlike our earth. 936. The direct rays received from the son on mountain-topshave than those which reach valleys greaterwarming capacity ; why, then,
is the earth
937. Is It is
so
much
must
it from distinguish
temperature,
colder in the former
glassequallytransparentto
nearlyopaque
to waves
twice
as
a
localities? ethereal
long or
waves
half
the
of all lengths?
lengthof lightwaves.
byGoogk
Digitized
62
SXERdBES
054.
How
would
proYO
you
IK
PHYSICS.
that
white
mixed
lightis
colored
light? 955. The The
956.
what
lightof
a
shortest
flame is monochromatic
salted Bunsen
wave-lengthswhich
a"Eect the eye
can
?
why
;
produce
sensation? color of
957. The
a
body
above
525^ C.
depends upon
but below this temperatureitscolor is not
its
temperature, affected by temperature.
Explain. 958. What
named falsely
color is due to the absence of stimulation
of any of the nerve-ends ? 950. All color perceptions are of
one
or
the simultaneous
to
tion excita-
of three sets of nerve-ends
more
the red and
When
due
nerve-ends
green
(we may call them). equallyexcited,what color
are
results?
combining complementarycolors ?
960.
What
is the result of
961.
What
is the result of
combiningany
two
colors that
not
are
complementary to each other? should
Why
962.
the
lens objective
microscopebe both achromatic 963.
State the
uses specific
and
of eye-pieces ? aplanatic
and
of the
the
lens objective
and the
a
pound com-
eye-glass
of the
compound microscope. 964. What is planepolarized light? 965.
At
In what
rightanglesto 966.
Put
a
the vibrations of
planepolarizedlight? *^the plane of polarization."
direction
are
littleoil in the center
of
sheet of paper. Hold the Is it by lightreflected from
a
paper between your eye and the window. the paper, transmitted by the paper, or
by both,
that you
see
the
paper? 967. Which
part, the oiled
or
the
clean, appears
lighterand
brighter? Why? ; let the lightof the window your back to the window Which strike the paper. portionnow looks brighter? Why?
968.
Turn
969.
How
970.
What
does
the oil affect the
is your
of the paper translucency black body? conceptionof a perfectly
energy is there in the invisible radiation of the candlo-flame? 971. How
much
?
light-wavesexcluding the 12
ft.-lbs.per minute.
"
Thomson. 972. What
are
the three
primary
color
sensations?
Bed, green,
and violet.
byGoogk
Digitized
973. What
are
63
ENERGY.
BADIANT
the artist'sthree
primarypigments? Red^ yellow,
and blue. shows that color is merelya sensation? phenomenon plainly Color-fatigpie. 975. What two pigmentsmixed will produce orange? two pigments will produce green ? 976. What two pigments will produce violet? 977. What the secondarypigments? 978. What are 979. What are tertiary pigments? 980. Name some pigments. Citrine, tertiary russet,and olive. 981. What pigments produce an olive ? Orange and green. 982. What pigments produce a russet ? Orange and violet. 983. What pigments produce a citrine ? Green and violet. ing shades of any colored pigment produced? By mix984. How are
974. What
dark with the
color. original
985.
What
is indigo? A shade of blue.
986.
What
is amber?
987.
What
is purple?
988.
YiThat
are
tints of
pigments? A pigment produced by the original color.
lightpigment with is pink? 989. What
a
990.
What
shade of green. A shade of violet.
A
A
tint of crimson. A
is straw? ?
What
is cream
992.
What
is azure?
993.
What
is lavender?
995.
When
996.
Draw
another
Draw
is blue
tint of
tint of orange. A tint of blue. tint of violet.
A
glass?
is a medium
denser than another? optically a line to representthe surface of a body of water. line cuttingthe latter obliquely, to representa pencil
thrust into the water.
Draw
said to be
a
broken
positionof the pencilthat is under 997.
The
absolute
indices
1.33 are disulphide respectively of lightin passingfrom 998. Give the philosophy of 999
.
line to
representthe apparent
water.
of refraction
of water
and
Also between
1001.
Does
what
an
carbon of
fraction re-
after-image.
other two
the index of refraction
strike the light-waves
and
1.64 ; what is the index the former into the latter?
The index'of refraction is a ratio between what two
1000.
which
yellow.
A
991.
994. What
ing mix-
surface of
? quantities
? quantities
depend a
new
upon
the
with obliquity
medium?
byGoogk
Digitized
64
EXERCISES
1002.
Is the
critical
IN
PHYSICS.
angle of diamond
relatively large or small?
Why? 1003.
Draw
passing from a denser representa light-ray medium, and representthe anglesof incidence, refraction,
into
a
and
deviation.
rarer
1004. a
How
line to
a
small
difference of
a
temperaturemay
be detected with
?
bolometer
Yihnsdegree F. 1005. Is temperaturea propertyof radiations? 1006. Sunlightis originally blue. How is it changed to white? 1007. The diminishingof chemical affinity through the agency of
ether-waves is called what? At
1008.
what
temperature does
platinum begin
be
to
red?
525" C.
temperaturedoes platinum become white ? 1300^ C. is magneto-opticrotation? When of plane 1010. What a beam polarizedlightpassingthrougha transparentbody placedbetween the poles of a powerful electro-magnethas the plane changed so that, 1009.
when
At
what
it emerges
from
the medium, the ether-vibrations
are
in
a
ent differ-
due to plane,it is said to have undergone a rotarypolarization magnetic influence. 1011. Suppose that an image of a flame is projectedby a convex lens on a screen, then the lens is submerged in a rectangular tank filled with
the
image
to make
to move it be necessary the screen distinct? if so, in what direction? "xplain. water
; wDl
1012. If the tank
were
filled with
carbon
what disulphide,
would
happen ? flyingbullet impinges on sound is produced ; state the various 1013.
A
a
target,and
a
transformations
flash of
lightand
of energy
that
occur.
1014.
and
What
is
a
photophone?
An
apparatus for the production
and transmission of sound by reproduction is it constructed? 1015. On what principle
the agency An
of
light. undulatorybeam
ance lightacts upon a substance called selenium,whose electrical resistis extremely sensitive to changesof temperature. Fluctuations of electricity in its resistance cause a current traversingit to become undulatory,and an undulatorycurrent produces sound-vibrations in a telephone-receiver. 1016. What phenomena can be shown with a pairof tourmaline tongs? of
Digitized by
RADIANT
Describe
1017.
65
ENERGY.
the surface which
hot-water
a
should
vessel
have
in order to retain its heat well.
Suppose
1018.
a
placedin water, and
a
water
and lens; what
would
be the
same
plano-concavehollow
as
beam
of
lightwere
be the effect
would that of
lens filled with
were
transmitted on
through the light,ue. the effect
the
glass lens of what Mnd
a
air
when
used in
air? 1019. windows 1020. vapor
What
would
"
of green What name
be the effect of
having the
outer
or
"
storm-
glassand the inner windows of purpleglass? is given to the temperature at which watery
in the air
1021.
Does
aqueous vapor 1022. What
quantityof and the 1023.
beginsto condense ? the humidityof air depend on presentper cubic yard? is relative humidity? It is
vapor
presentin
a
it can
does the statement
Why clear sky? on
is dew
a
depositedmost
a
the
giventemperature
contain at that
that the relative
is 40 per cent mean? which 1024. State the principle on 1025.
ratio between
the
cubic foot of air at
greatestquantitywhich What
the absolute quantity of
temperature. of humidity,
air
is constructed. hair-hygroscope in stillair ? under a copiously
the best radiators?
byGoogk
Digitized
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