O Level Physics Questions
Short Description
O level Physics...
Description
Understanding
through
Problem Solving
A Supplementary Practice • Latest MOE syllabus • Topics are categorised into easily manageable sections • Questions are arranged in increasing level of difficulty to facilitate a better mderstam • Question types .. simple recall to foh .. analysis an~ synthesis - an aspect in tackling data-sJem ",n
David Oon
'0' Level
COI>yright ~ 2()(YJ Panpac Education t·rivatc Limited
Published by EPB Pan Pacific
-
An imprint of Panpac €ducsti().nPrivate I..i.mitcd
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EI'B Pan Pacinc is a trademark ofTirncs Publishing Limited ISBN 918·981·273·004-6 First publiShed 2007 ReprinlBd 2008 Author: David Oon
Editor: Chan Shyong Ya\v
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Theme 1
>- Measurement
Chapter 1
Physical Quantities, Units and Measurements 1.1 Base Quantities, Units and Prefixes ].2 Errors in Measurements 1.3 Length Measurements with Calipers and Micrometer Time Measurements and the Penduhllu 1.4 1.5 Scalars, Vectors and Vector Diagram Challenging Segment 1.6
Theme 2
>- Newtonian Mechanics
Chapter 2
Kinematics 2.1 Sl2eed, Velocity and Acceleration 2.2 Graphical Analz:sis of Motion 2.3 Freefall Challenging Segment 2.4
Chapter 3
Chapter 4
Chapter 5
1 1
2 3
6 1 9
U U
l..4
22 24
Dynamics Balanced Forces 1.1 IInbalanced Forces 1.2 3.3 Friction 3.4 ChaUenging Segment
21 21
Mass, Weight and Density Mass and [nerti;) 4.1 Weight 4.2 4.3 Density and Flotation 4.4 Challenging Segment
:N 32
Turning Effect of Forces 5.1 Moments 5.2 Princil2le of Moments 5.3 Centre of Gravity and Stability Challenging Segment 5.4
43 43
28
11
3.3
4:0 4..1
42
~
4!i
4.8
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Chapter 6
Pressure 6,1
Pressllre
6.2
Liquid Pressure and Atmospheric Pressure Pressllre Difference Hydraulics
6.3
6.4 6,5 6.6 Chapter 7
Pressllre Measurelnent
Challenging Segment
Work, Energy and Power 7,1 Work 7.2 Kinetic Energy and Gravitational Potential Energy 7.3 Principle of Conservation of Energy 7.4
Power
7.5
Challenging Segment
Theme 3
:> Therma1 Physics
Chapter 8
Kinetic Model of Matter 8.1 States Qf Matter and the Kinetic MQdel 8,2 Brownian Motion 8.3 Challenging Segment
Chapter 9
Thermal Energy Transfer 9.1 Thermal Equilibrium 9.2
9,3 9.4 9.5 Chapter 10
Conduction
Convect jon Radiation Challenging Segment
Tenlperalw'e 10.1 Principles of Thermometry 10.2 Thermocouple Thermometers 10.3 Challenainz Seament
Chapter 11
Thermal Properties of Matter 11.1 Heat Capacity and SpeCific Heal Capacity 11.2 Melting, BoiJing !U1dEvaporation 11.3 Latent Heat and Specific Latent Heat 11.4 Challenging Segnlent
49 49 50
5S 57
58 59 61
61 63
65 68 69
73 73
7S
76 79 79
79 81
82 83 87 87 89
90 91 91
94 96 100
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Thenle 4
» Waves
Chapter 12
General Wave Propenies 12.1 Longitudinal and Transverse Waves 12.2 Wave Terms and Graphical Representation of a Wave 12.3 Ripple Tank 12.4 Challenging Segment
1.03
Light 13.1 Reflection 13.2 Refraction 13.3 Total Internal Reflection 13.4 Thin l.enses 13.5 Chal.lenging Segnlent
109
Electromagnetic Spectrum 14.1 Properties of Electromagnetic Waves and Applications 14.2 Challenging Segment
119
Chapter
13
Chapter 14
Chapter 15
Sound 15.1 Sound Wave and its Graphical Representation 15.2 Speed of Sound 15.3 Echo and Ultrasound 15.4 Challenging Segment
Theme 5
» Electricity and Magnetism
Chapter 16
Static Electricity 16.1 [aws of Electrostatics 16.2 Eleclrostatic Charging 16.3 Electric Field 16.4 Challenging Segment
Chapter 17
Current of Electricity 17.1 Current 17.2 ElectTomotive Force (E.M.F.) and Potential Difference 17.3 Resistance 17.4 Ohm's Law 17.5 Challenging Segment
un 1.04
J..06 107 109
I11 ill ill ill
119 120 12.3.
ill
126
127 ]28
ill l.3..l
132 ill l..34
ill 131 138
ill
.lAO. 141
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Chapter
18
D.C, Circuits I R.l Series C'i[cilit 18.2 Parallel Circuir 18.3 Series and Para liel Ci [CU ill' 18,4 Potentilll Divider Circuits 18.5 Use of Cathode-Ra~1 Oscilloscope 18.6 Challenging Segment
143 14.3
144 146 141 148 150
Chapter 19
Practical Electricity 19.1 Electric Power and Ener,!!,y 19.2 Dangers of Electricity 19.3 Safe Use of Electricity 19.4 Challenging Segment
153 153 154 156 157
Chapter 20
Magnetism 20.1 Laws of Magnetism and Induced Magnetism 20.2 Magnerisation and Dema~netisation 20.3 Magnetic Field 20.4 Challenging Segment
161 16l 163 164 165
Chapter 21
Electron,agnetism 21.1 Magnetic Effect of a Current 21.2 Force on a Current-Carrying Conductor 21.3 Tbe nc Motor 21.4 Challenging Segment
167 167 169 173
Electromagnetic Induction 22.1 Principles of Electromagnetic Induction 22.2 The A.C. Generator 22.~Transfo[lllf~[ and POll"er'Iransmisaion 22.4 Challenging Segment
177 177 179 181 184
All~~ers and Worked Salutians
189
Chapter 22
I :z I
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SUMMARY OF KEY QUAi~'rrrIES,SYMBOLS AND lJNITS Quatity
Symbol
Unit
Length Area
I, h ...
Volume
V W m, M
km, In, em, nun m2 , emm:l, em"
Weight Mass Time
A
I
Period"
T
Density"
p
Speed" Acceleration+
Acceleration of free fall Force"
Moment of force* Work done Energy Power Pressure Atmospheric pressure Temperature Heat capacity Specific heat capacity Latent heat Specific latent heat Frequecy Wavelength Focal length Angle of incidence Angles of reflection, refraction
l'
1.1"
a
s
F, P W,E E
P p,P {J, T
C
N*
kg, g, mg h, min, S, ms s g/cm', kg/rn" krn/h, mis, cm/s mis' rn/s', N/kg N Nm J*, kWh* J
\"'1* Pa*, N/mz use of rnilibar °C , K J/oC,
I
I/K J/ (g °C), J/ (g K) J J/ kg, J/ g
.f,
Hz
c L
r
m, cln In, ern degree (0) degree
c
degree (0)
II-
.f I
(0)
Critical angle Potential difference*/voltage Current"
Charge e.m .rr-resistance
V
I q, Q E R
V*, mv A, IliA
C,A V Q
S
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Physical Quantities, Units and
~~.r~~~/~m~e~as~u~re~m~en~t_s~ >-
1.1 Base Quantities, Units and Prefixes
1.
John, who has a mass of 50 kg. height of 1.54 In, is able to run a distance of I km in a time of 5 min 12 s. His average speed was calculated to be 3.21 rals: (a)
Write down all the physical quantities and their respective SI units for the situation above.
Physical Quantities
Which
(b)
[2J (c)
What
of
the
other
(5)
SI units
quantities
base
above
quantities
are
are considered
there
besides
as base quantities?
those
in (b)
above?
[4J (d) Which prefix has been used in the situation above? State how many times is the factor
of
2.
[2J
this prefix over its base unit.
Ali said, "I found out that the speed of light in space is 3 x 10" In/s. This means that light can travel a distance of 3 x 10" m in a time interval of just 1 second!" (a)
(b)
Identify and write down from what ALisaid, all the base physical quantities and their respective SI units.
(2)
Rewrite the distance of 3 x IU' m using the prefixes kilo-, mega- and giga-.
[3J
3 x 10" nl (c)
=
kin =
Min =
Gm
Convert 3 x 10" nl/s into: (i) km/s,
(21
[21
(ii) km/h,
Chapter I
1
-~..-
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3.
Alice calculated the density of a solid metal box by first measuring the mass and volume of the box. The results are as follows:
Mass = 300 g
Volume = 60 em'
Density = 5
glcm' (a)
Out of the three physical quantities above, which are not considered as base quantities?
[2)
[6]
(b) Convert for all three quantities above, into their respective SI units.
-
_
Volume: 60 em' -
_
Density: 5 g/cm? -
_
Mass
: 300 g
> 1.2 Errors in Measurements 1.
(a) Write down the
tWO
types of errors that may be present during measurement.
(b) State which of the errors above can be reduced by taking a larger number of measurements and averaging?
2.
(2)
[I]
State the main type of error for each of the tWO cases below. Explain your choice of answer and describe how in each case, the error can be reduced. (a) Bala and Billy have a digital stopwatch each. Both measures the time taken for a marble to roll down a l-m ramp and the results are 3.57 s and 3.42 s respectively. Type of error:
_
Explanation and description on how to reduce error:
(b)
[I) [2]
A glass cylinder has a length specified by the manufacturer as 15.0 cm. Bill wanted to measure and confirm this length. He used a metre rule, unaware that it has a defective scale at the zero mark. His measurement result is 14.8 cm. Type of error:
_
Explanation and description on how to reduce error:
.
_2
. Understanding Physics through Problem Solving
[1] [2]
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material
3.
Bob is trying (0 determine the period of a 1.2 m long pendulum. He first measures the time interval for 10 complete oscillations with a digital stopwatch. He then carries out an averaging to determine the period of oscillation. Suggest two ways in which he can make the results more accurate.
clamp
[2]
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r I
r
,
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,
,, ,
,
,1=1.2nl
,,
,;"
\ ......
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>- 1.3 Leng!h Measurements with Cali ers and Micrometer 1.
Write down the readings for the following measurements below. The following pairs of cal ipers have no zero error. (a)
20
30
=
[I]
Reading =
[I]
Reading
(b)
2.
Write down the readings for the measurements below. This pair of calipers has no zero error.
(a)
o Illllllllll
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5
10
Reading =-----lIJ 5
4
(b) Reading
1IIIIIIIIIIIIIIfllllllili em
7
=
[I]
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3
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3.
A pair of faulty calipers is found to have a zero error of +0.03 cln when the jaws are fully closed. This pair of calipers is used to measure the depth of a beaker.
1111111111111111111111111 em
4.
9
10
(a) Write down the measurement made with this pair of faulty calipers.
(I)
(b) Write down the actual depth of the beaker.
[1]
(c) State the pan of the vernier calipers used to measure the depth of the beaker.
[I]
A pair of faulty calipers is found to bave a zero error of -0.01 ern when tbe jaws are fully closed. This pair of calipers is used to measure the diameter of a syringe.
o 1
5
em
S.
IIIII
I I II
111111111[1111111111111111
10
1
3
4
(a) Write down the measurement made with this pair of faulty calipers.
[1)
(b) Write down the actual diameter of the syringe.
[1]
(c)
(2)
Describe what you would do to obtain a more accurate diameter of the syringe.
Write down the two measurements below made with a micrometer. Assume that the micrometer has no zero error.
(a)
(b) ~,=".-~n 10
'~lM,§--J5 o Reading =
4
'-----'
[1]
Reading = -----[1]
Understanding Physics through Problem Solving
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6.
The diagrams below shows four measurements of a diameter of a non-uniform iron rod made with a micrometer. ~l=:--~n3S 30
WI-_~_'25 Measurement 1
Measurement 2
Measurement 3
Measurement 4
(a) Record the readings of all four measurements in the table below.
Measurement No. Initial measurements Corrected measurements
I
2
3
14] 4
(b) A student checks the micrometer and finds that it has a zero error of -0.02 mm, Correct l4] all four earlier measurements and record them in the table above. (c)
7.
Calculate the average diameter of the iron rod.
[21
(d) State the type of error present in this situation.
[II
A faulty micrometer screw gauge with an error of -0.02 nun when the jaws are fully closed is used to measure the external diameter of a test tube. (a)
Write down the measurement shown on the micrometer.
_
[1]
(b) Write down the actual diameter of the test tube. 8.
_
[IJ
A faulty micrometer screw gauge with an error of +0.02 mm when the jaws are fully closed was used to 111eaSUrtehe diameter of a washer. (a)
Write down the measurement shown on the micrometer.
_
[II
(b) Write down the actual diameter of the washer.
_
[ll Chapter I I
_
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:> 1.4 Time Measureme ts and the Pendulum 1.
The diagram below shows a simple pendulum setup in a school laboratory. The average time taken for the bob to move from Q to R is 0.4 s.
clamp
[u
(a) Define the period of an oscillation.
(b) What is the period of the pendulum?
r
r
, ,
",, ,
,
I
, , ,, ,, ,, ,,
,, ,, , , ,
-
[1]
,,
-
P"-" Q
R
(c) The pendulum experiment allows us to calculate an approximate value of Earth's gravitational acceleration with a simple formula. Gravitational acceleration = 41t2X (i)
length of pendulum bob in metre square of period of osci llation in seconds
The length of pendulum in this experiment is 0.65 m. On the diagram above, IIIark the length of the pendulum.
[1]
(ii) Using the value found in (b) and length of pendulum as 0.65 m, calculate the gravitational acceleration of Earth in nl/s2.
(2]
(iii) How must the length of the pendulum be adjusted to increase the period of the pendulum?
[I]
(iv) A student proposes to use a bob that is heavier in order to lengthen the period of the pendulum. Explain if the proposal is valid. [2]
2.
The diagram below shows a setup of a simple pendulum suspended from a clamp. The pendulum bob is moved about 5° to J and released, causing the bob to oscillate between positions J and L. The bob takes an average of 0.60 s to move from J to K and to L. (a)
What is the period of the pendulum above?
(b) What is the time taken for the pendulum to make 2.5 oscillations?
[I)
clamp
,,,",,, ,, ,
[I]
,, ,1. ,
I
,
I
I
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K
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(c) Marcus lengthens the pendulum and proceeded to measure the rime taken for the pendulum to make 20 oscillations. Marcus uses a digital stopwatch. The process is repeated four more times and the results are as follows: 35.26 s (i)
36.23 s
34.83 s
34.94 s
36.02 s
Calculate the new period of the pendulum by averaging. Show your workings clearly.
(ii) Calculate the frequency of oscillation of the pendulum.
[2]
12]
(iii) Explain why the determination of the period of oscillation is more accurate by
calculating the average of 20 oscillations and not from one single oscillation? [I)
(iv) The method used in (i) and (ii) is useful to minimise what type of error?
The diagram below shows a box acted upon by two forces. 1.
(a) State the resultant magnitude and direction of the
box due to the two forces.
51'1
~I b
ox
[I]
8N
[2]
(b) The 8-N force is now reversed. State the resultant magnitude and direction of the box
due to this change. The 5-N force remains the same, [2]
2.
A vector of size 6 units, points directly north while another vector of size 8 units, points east. Draw a parallelogram to determine the vector addition of these two vectors. Use a scale of 1 cm : 2 units. Stat.e the magnitude and direction of this resultant vector. [5]
Chapter I
7
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3.
Force is a vector quantity. Two forces of 6 N each acts on an object. (a) Describe how it is possible to produce a zero resultant force from the two forces.
(2)
(b) Describe how it is possible to produce a resultant force of 12 N from the two forces.
[2]
(c) Draw a vector diagram to show how a resultant force of 6 N may be obtained from the two forces of 6 N each. Label the 6-N forces and the resultant force clearly. [2J
4.
The diagram below shows two forces of 30 Nand 40 N acting on a crate. JON
crate
Draw a parallelogram to determine the resultant force of these tWOforces. Use a scale of I ern : 5 N. State the magnitude and direction of the resultant force.
8
Understanding Physics through Problem Solving
[5)
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5.
Which of the following diagram correctly shows the addition of the 3-N and 4-N forces?
A 3N
c
B SN
51'1
IN
4N
51'1
3N
41'1
D 51'1
3N
41'1
41'1
1
r
>- 1.6 Challeng!ng S~ment 1.
A pair of calipers has a zero error of +0.2 mrn. Alan uses it to measure the length of a cubic dice. The reading is 12.6 mm. Recognising the error in the calipers, Alan makes adjustments to his reading and recorded the length of one side of the dice as 12.8 mm. He then proceeds to calculate the volume of the dice and writes down the result as 2 097 mrn", (a)
(3)
State the three errors made by Alan.
(b) Which of the quantities above is a derived quantity?
2.
Two forces act at right angles at a point 0 as shown below. What is the resultant of the forces shown? Magnitude
A B C
D
3.
15 N 15 N
21 N 21 N
[l]
Qr - - - - - - - - - R
Direction
OQ PR OQ PR
91'1
p
12 N
o [
)
Two forces are combined and cause a resultant force.
[l)
(a) State the one factor that affects the magnitude of the resultant force.
(b) State the range of the magnitude of the resultant when forces of magnitude 3 Nand 4 N
[1.1
are combined.
4.
James, starting at a point P, walks due North for one hour at a constant speed of 4.0 km/h and then, at the same constant speed, walks 4.0 km due East, finishing at a point Q. In the same total time but at a different constant speed, Jo walks directly from P to Q. Determine
(a) the total distance walked by James.
[2)
Chapter 1
9
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(b)
by drawing. the distance walked by Jo,
(c) the velocity of Jo.
5.
[5)
l2J
The reverse bungee is II new and excinng form of fairground ride first introduced in 1999. Passengersboard a spherical cage. and arc then released vertically upwards into the sky. The cage is pulled upwards by a pair of elastic cords mounted on the side of the cage. The diagram shows the forces acting on the spherical cage. Each force has a size of 40 kN each.
By means of
scale drawing, determine the magnitude and direction of the resultant force exerted by both elastic cords on the spherical cage.
10
"------'
II
Underxtendiug 1)I,y:..ic!1o Ihl'ou~h Problem Solving
(,opyngl1ted m'lter" I
B 1.
Kinematics
(a)
How is displacement different from distance?
12]
(b)
Which of (he quantities above is a vector?
II]
(c) Kathy throws a ball upward into the air and caught it at the same position when the ball returns to Earth. Evaluate the following statements below, making the neccessary corrections to statements that are false.[5]
Mid-point of downward motion
4m
Point ofthrowing
b.1l
(i)
True I False
The distance travelled by the ball is 8 rn.
(ii) The displacement of the ball at the point that it is caught is +4
2.
True I False
111.
(iii) The height reached by the ball is equal to the total distance travelled.
True I False
(iv) The displacement of the ball at the highest point is +4 m.
True I False
(v) When the ball is mid-way on its downwards motion, its displacement is ·2 111.
True I False
The diagram on the right shows a spring suspended from a retort stand. A bob is hung below the spring, causing the spring to be extended to the neutral position shown. bob
The bob is then pulled downwards to position J which is neutral 8 cm below the neutral position and then released. This position causes the bob to oscillate between positions J and K repeatedly.
K
\ - - - - -
- - - - -
!
one complete up 1.
o
Upwards and equal to the weight of the ball. Upwards and less than the weight of the ball. Zero because the weight of the ball is equal to air resistance. Downwards because the weight of the ball is more than air resistance.
(
]
.2 Untialanced F~ A 2 kg box is under the influence of2 forces as shown. Evaluate the following statements about forces for true or false. Make the necessary corrections 10 statements that are incorrect. [4)
(a)
Box is under the influence of unbalanced forces.
~ I 14N
~
(b) The net force acti ng on Ihe box is zero. (c) The box will move towards the right at constant
~--
I
24 N
True
)-
I
False True I False True
speed.
I False
The acceleration of the box is 5 Tn/s' towards the right.
True I False
(d)
(e)
If the 14-N force is increased (024 N, the box will continue
movi.ng at constant speed. (I)
If the 24-N force is reduced to 14 N, Thebox will slow down.
True I False True I False
..._
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Understanding Physics through Problem Sotving
COPYrightedmatenal
2.
The diagram below shows a bus of weight 20000 N moving at a constant speed of 3 m/s. The bus experiences a total retarding force of 8000 N. This retarding force includes friction between the bus, the road and air resistance. Its engine provides the forward force that enables the bus to move forward.
(a)
Is the bus moving under balanced or unbalanced forces? Explain.
(b) State the net force acting on the bus.
3.
[2J
_
[IJ
(c)
State the magnitude of acceleration of the bus.
_
(d)
Indicate with arrows and label the forces acting on the bus in the diagram above. (There should be four forces acting on rhe bUS.)
[I) 1'41
The diagram below shows a carom puck of mass 0.05 kg resting on a smooth carom board. It was given a quick push force of 4 N.
(a)
Is there other forces acting on the puck besides the 4 N push force? Explain. If there are other forces present, indicate and label them on the diagram above. [3]
(b) State the net force acting on the carom puck.
_
[I)
(c)
Is the carom puck under balanced or unbalanced forces? Explain.
(2)
(d)
Calculate the acceleration of the carom puck. Show the equation used clearly.
(2)
Chapier 3
29
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4.
[I]
(e)
The equation used above is a representation of which of Newton's Law?
(1)
Calculate the final velocity of the puck if the time of impact between push and puck is just 0.05 s. [3]
The diagram on the right shows a lift of weight 5 000 N under the influence of an upward force provided by its attached cables.
rd force 4800 N UpW3
lift cabies
(a) Is the lift under balanced or unbalanced forces? Explain. [2] ~
5.
r- lin
~
(b) Calculate the acceleration of the lift given the acceleration of free fall is I0 In/s~.
[2]
(c)
[2]
Is the lift moving upwards or downwards? Explain.
The diagram on the right shows the velocity-time graph of a 800·kg lift that started from rest at the first floor until it stops ar the 3'" floor of a building. (a)
vetociry/rn s'
1.2
State the time interval(s) when the lift is (i)
under balanced-forces and.
(ii) unbalanced forces?
_ _
[2J
++-----4--'\--+
o
(b) State the net force acting on the lift during the 1 to 6 s interval? (c)
8
_
tirne/s
[1]
From. the graph, calculate the net force acting 011 the lift between the 0 to I s interval. [21
---- 30
6
Understanding Physics through Problem Solving
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3.
The diagram on the right shows a car of mass I 500 kg initially at rest. The car's engine provides a forward force that causes the car to accelerate LO the right at a rate of 1.2 n1/s2. (a) Ignoring the effect of air resistance, state and explain the size of friction acting 00 the car when it is at rest. [ I]
(b) Calculate the net force acting on the car.
(c)
(2]
From your answer in (b), lind the size of friction acting on the car if it is known that the forward force is 3 000 N. [2)
(d) The car reaches a speed of 6.0 m/s after 5 s. The forward force is now reduced to 1 200 N. State the net force acting on the car now. [1]
(e)
Describe and explain the motion of the car after 5 s.
[2]
(f)
Sketch a speed-time graph of the car up till 10.0 s.
[1]
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Understanding Physics through Problem Solving
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You have either reached a page that is unavai lable for vi ewi ng or reached your vi ewi ng Iimit for thi s book.
(b)
3.
4.
From your results in (a), calculate the acceleration of the object.
A test was carried out on a newly designed car of mass of I 400 kg. It was moving at a steady
speed of 20.0 m/s for 5.0 s before crashing into a wall. It came to a rest in 0.4 s. (a) State the net force acting on the test car during the first 5.0 s of the lest.
[1)
(b) Find the average force exerted on the car during the collision.
(2)
A train of mass 6.84 x 106 kg is moving at a speed of 80 km/h. The brakes, which produce a net backward force of 1.93 x lQ6N, are applied for 25.0 s, (a)
What is the new speed of the train?
[2]
(b) How far has the train travelled in this lime?
5.
[2]
[3]
The figure below shows a wheel of a truck as it is about direction of friction acting on the wheel.
10
move off. Label on the diagram the
[1]
direction of motion
'--_
34
....
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(c)
e
In further investigations, the student determines the variation of tan with the horizontal force exerted by the spring. The values of tan and length of the spring is given in the table below. Complete the table by filling in the empty blanks.
e
0.123 10.005
lanS Length of sprin2/m
0.385 10.015
0.532 10.022
0.755 10.030
Extension, .r/m
0.04
Size of' spring forcelN
16
e against magnitude of the force in the space below.
Plot a graph of tan
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Use your graph to determine the angle
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[I]
'-----'
38
Understanding Physics through Problem Solving
Copynghted malenal
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>- 4.4 1.
~eDt
Robert wants to calculate the density of a type of wood. He measures the mass and volume of different sizes of wood samples, Which graph shows his results?
B
A U13SS
mass
OlliSS
:f-----
o
D
C
volume
n13SS
o
volume
[
]
2.
The diagram on the right shows two cubes made out of identical material. One cube has sides that are twice as long as the other cube. If the weight of the small cube is W, find the weight of the larger cube in terms of m, where III is the mass of the small cube. [4J
3.
A metal block of dimension 5 cnl x 5 em x 8 em and has a density of 4.5 g/cm' is released from a great height. Calculate the air resistance acting on the metal block when it reaches terminal velocity. (3)
4.
(3)
Clara made this statement, "Hey! I just found out that our weight drops when you are high up in the sky." Is Clara's statement true? Explain. (2)
(b) Dolly who heard Clara's statement was curious. She tried this out during a holiday trip and was overjoyed. She told her friends this, "J just found out how I can lose weight very quickly. Just take a trip by plane. When the plane is high up in the air, step on a bathroom scale and you will find that your weight has reduced! What a great way to lose weight! No more dieting or slimming pills!" Is Dolly's statement valid? Explain. [3]
""---- -
4 2
Solving
Understanding Physics ihrough Problem
Copyrighted material
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>- 5.3 Centre of Gravit! and Stabilit! 1.
(a)
Define centre of gravity.
(2)
[1]
(b) A long uniform object usually has its centre of gravity at its (c) The diagram shows a 2-m uniform rod of mass 5 kg.
A
(i)
Mark on the diagram the centre of gravity of the rod with an X.
[1]
(ii) State the distance of X from end A of the rod.
_
[1]
(d) The rod is placed on a pivot that is 80 cm away from end A. (i)
Mark the pivot in the diagram above with a triangle, 6..
(ii) Describe what will happen to the rod.
_
[1)
(e) Calculate the moments and state its direction for (d) above.
(f)
[2]
Where must the pivot be placed in order for tbe rod to balance?
_
[1]
2. The figure below shows a 20 N cantilever hinged at point P. Its centre of gravity is at point C. (a)
20 em
30 N
Calculate the force F needed to keep the cantilever in equilibrium. [4]
50cm 10 em
,~
5 em•• p 40N weight
(b) The three forces, 30 N, 40 Nand F are removed. Describe and explain what would happen to the cantilever about point P. Use the term moments in your explanation.
....._ ...I
4 6 Understanding
.. ..
(2]
Physics through Problem Solving
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(b) If more mercury is added to B such that mercury level in A rises by 2 ern, describe and explain what happens to the level of mercury at B? (2)
(c) If some air is introduced to the space above A, the difference in level of A and B becomes 600 mrn, Find the pressure of air in the space in mrn Hg. [2]
7.
Two simple barometers are used to measure pressure. Calculate the height of a column of water which wiU exert the same pressure as 20-cm column of mercury. The density of mercury is 13.6 g/cm" and water is 1.0 g/cm"
--------
water
mercury
8.
The figure shows two vertical tubes P and Q partly immersed in a vessel containing mercury. The space above the mercury in tube P is empty of any gas. There is a small amount of air in the space above the mercury in tube Q. Mercury bas a density of 13 600 kg/nr' while the gravitational field strength is 10 N/kg. (a)
Write down the atmospheric pressure in cm Hg from the data above. [I]
(b) Calculate the pressure in Pa, exerted by air above
mercury level in Q. (3)
p
- -- f-. 77 em
Q
- 60 em
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(b) Calculate the pressure of the trapped Liquid.
[2]
(c) If the small piston moves down by 8 ern, calculate the distance moved by the big piston. [3]
> 6.5 Pressure Measurement 1.
The figure shows some carbon diox ide gas trapped in a cylinder fitted with a tight piston. The carbon dioxide gas pressure of value C exerts a force F on the piston which has a surface area S. Volume of trapped gas is V. (a)
surface, area, S gas pressure, C
Write down an equation that correctly shows the relationship between F, C and S.
[IJ
(b) Calculate the pressure of the carbon dioxide gas inside the cylinder given that the surface area S is 0.008 m', and the force acting on the surface F is equals to 40 N. [2]
(c) The piston was pushed further into the cylinder, causing the volume occupied by the carbon dioxide gas to reduce by 200/0. Calculate the pressure of the carbon dioxide gas inside the cylinder. [3]
......
58.... Understanding
Physics through Problem Solving
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5.
Sam pushes a shopping trolley of mass 30 kg for [6 m. The work done by him is 2 kJ. (a)
What is the force exerted by Sam on the trolley'?
[2J
(b) Some additional groceries are added to the trolley. The trolley is then lifted vertically off the ground for 25 III by a lift system that did 10 kJ of work. The Uft moves at a constant speed. (i)
[2J
What is the force exerted by the lift in raising the trolley?
(ii) Calculate the mass of the added groceries.
6.
[3)
A tractor is pulling a fallen tree trunk along a rough road horizontally. The tree trunk weighs 2500 N. The tractor is moving at a constant speed of 1.2 nl/S for 5 s. The pull force exerted by tractor on trunk is II kN. (a)
[2J
Calculate the distance travelled by the tree trunk for 5 s.
(b) Calculate the work done against friction between tree trunk and the rough road.
,
--'6- 2.....
[3J
Understanding Physic"! thc()tJg_hProblem Solving
Copyrighted material
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3.
A wooden box initially at rest slides down a smooth slope AB and onto a smooth horizontal ground as shown in the diagram below, The distance .of the slope is 4 m. A
300 .L
B
c
(a) Calculate the speed of the block when it reaches point C. 4 m away from the slope,
(b)
4.
[2]
A basket ball is dropped onto the floor, As the ball bounces up and down, the height of each bounce gradually decreases. During the motion of the ball.
A B C D 5.
Describe and explain what happens to the box after it reaches poinr C.
[3]
the kinetic energy of the ball is constant. the potential energy of the ball is constant. the sum of the kinetic and potential energies of the ball is constant. the total energy of the ball. ground and air is constant.
[
1
A bQXof mass 2 kg slides from rest through a distance of 20 m down a frictionless slope as shown in the diagram. What is the kinetic energy of the block at the bottom of the slope? [3]
10m
'--
66
...
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2.
Figure A shows a 120 kg box which is projected up a rough incline with an initial speed of 40 m/s. The box returns to its starting point 15 s later with a speed of 20 rn/s. Figure B gives the graphical representation of the motion using a velocity-time graph. velociry/m g-I
Figure A
(a)
Figure B
(4)
Find the acceleration in the intervals. (i)
PQ.
(li) QR.
(b) Calculate the distance travelled by the box up the plane and back to its starting point. (2)
(c)
Calculate the initial and final kinetic energy of the box when it returns to its starting point.
(d) Suggest an explanation for the difference in initial and final kinetic energy in (c).
...._
...
70
[4J
[2]
Understanding Physics through Problem Solving
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3.
(a)
(2)
Explain why gases can fill all the space available to them.
(b) Explain how particles of gases exert pressure on the walls of its container.
4.
The diagram shows a container with one end closed. Some air is trapped inside the container by a piston. The piston can move free!y in and out of the container. The pressure of the trapped air is similar to atmospheric pressure.
air
[2]
sealed container
The container is heated until a steady temperature of 80°C is achieved. The piston starts to move outwards and comes to a stop when the temperature becomes steady. (a)
Describe and explain what happens to the force of collisions between air molecules and the inner walls of the container. [2]
(3)
(b) Describe and explain what happens to the pressure of the gas at 80 °C.
(c)
Based on the description above, state the relationship between temperature and volume of a fixed mass of gas when its pressure is constant. [I]
The piston is locked such that it cannot move. The container is then beated to 100°C. After some time, the container bulges outwards. (d) Explain why the container bulges outwards.
(e)
'--
74-'
[3]
Based on this observation, deduce the relationship between temperature and pressure of a [1] fixed Inass of gas when its volume is constant.
Understanding Physics through Problem Solving
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5.
(a)
l2J
Explain why the external surface of a metal kettle is usually painted shiny silver.
(b) Will water boil faster if a kettle with a shiny silver external surface is used instead of one
with a dull black surface? [2]
6.
The figure below shows a typical truck used to move fuel from a petroleum complex petrol kiosks.
10
fuellank
[2]
Explain why the outside surface of the fuel lank is always painted shiny silver.
)!>
1.
9.5 ChaUen' The figure shows a boiling-lube being healed. TIle rube contains boiling water at the top and ice at the bortom. It is observed that the ice at the bortom melts very slowly despite the boiling water at the tOp. (a) What does the experiment above demonstrate?
d'
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