DAILY PRACTICE PROBLE FOR NSO for Class IX

DAILY PRACTICE PROBLEMS FOR NSO DPP : 01

PHYSICS

Class –IX

1.

If the linear velocity of a particle is increased by 10% and angular velocity is also increased by 10%, then the percent change in centripital acceleration is : (A) 31% (B) 21% (C) 11% (D) 10%

2.

The earth makes one revolution in 24 hours. Calculate (i) angular speed of earth (ii) tangential speed of an object (linear speed) at the equator due to this rotational motion. The radius of earth is 6.38 × 106 m. 22    use    : 7   2 (A) rad/s, 440 m/s. 84400 (C) 7.3 × 10–5 rad/s, 465 m/s.

3.

2 rad/s, 440 m/s. 86400 (D) 7.9 × 10–6 rad/s, 470 m/s.

(B)

A body of mass 10 kg revolves in a circle of diameter 0.40 m, making 1000 revolutions per minute. Calculate it’s linear velocity. 200 2 20 m/s (B) m/s (C) m/s (D) 0.2  m/s 3 3 3 Which of the following statements is true for a planet ? (A) Its mass increases with increasing distance form the sun. (B) Its radius increases with increasing distance from the sun. (C) Its period of revolution increases with increasing distance form the sun. (D) Its period of rotaion about its own axis increases with increasing distance form the sun.

(A) 4.

5.

A body is moving with constant acceleration from A to B in a straight line. C is the mid-point of AB. If u and v are the speeds at A and B respectively. The speed at C is :

v 2 – u2 u2  v 2 (D) 2 2 A ball is dropped from a height of 7.2 m. It bounces back to 3.2 m after striking the floor. the ball remains in contact with the floor for 20 ms. Given that g = 10 ms–2, the average acceleration of the ball during the contact is : (A) 100 ms–2 (B) 200 ms–2 (C) 600 ms–2 (D) 1000 ms–2 (A)

6.

uv 2

(B)

v–u 2

(C)

7.

An arrow shot vertically upwards loses its initial speed by 60% in 3 seconds. The maximum height reached by the arrow is (g = 9.8 ms–2 ) (A) 122.5 m (B) 44.1 m (C) 100 m (D) 45 m

8.

During a cycle race, two boys happen to cross a point X simultaneously with speeds 16m/s and 12 m/s respectively. In order to win the race, they increase their speeds at the rates 1 m/s2 and 2m/s2 respec tively. Unfortunately both reach the final point Y at the same instant of time. If the time required to cover the distance XY is t, then : (A) XY = 120 m (B) XY = 160 m (C) XY = 200 m (D) XY = 180 m

9.

If a stone is released from a balloon moving upwards with certain velocity v0 at certain height above earth’s surface then velocity time curve of stone’s motion can be best represented by : (g = constant)

(A)

(B)

(C)

(D)

10. -

11.

A ball is thrown up vertically in still air with a velocity of 20ms–1. Itcomes back to ground. The velociyt Time graph is (g = 10ms–2).

(A)

(B)

(C)

(D)

A body of mass m is moving on a circular path of radius r with constant speed V. After half round the change in momentum of the body is : (A) mv

(B) 2mv

(C)

mn 2

(D) 4mv

14.

Which of the given distance-time graph (Figure) represents the accelerated motion of a body ?

(A)

(B)

Time 15.

(C)

Time

(D)

Distance

An aircraft has a take off velocity of 180 km/h. What length of run way is needed ? The acceleration of aircraft along the run way is 2.5 m/s2 : (A) 100 m (B) 150 m (C) 320 m (D) 500 m

Distance

13.

Distance

The average velocity of a body is equal to the mean of its initial and final velocities. The acceleration of the body is : (A) uniform (B) variable (C) uniformly variable (D) zero

Distance

12.

Time

The velocity-time graph for a body with non-uniformly accelerated motion is a : (A) straight line (B) straight line parallel to x-axis (C) straight line parallel to y-axis (D) curved line

Time

DAILY PRACTICE PROBLEMS FOR NSO PHYSICS 1.

DPP :

Class –IX

02

Velocity of a moving object is changing uniformly ansd the kinetic energy changes accordingly. Which of the following graph dipicts the correct relationship.

Kinetic energy

Kinetic energy (A)

(B)

Velocity

Velocity

Kinetic energy

Kinetic energy

(C)

(D)

Velocity 2.

Velocity

Two vessels A and B of different shapes have the same base area and are filled with water up to the same height h (see figure). The force exerted by water on the base is FA for vessel A and FB for vessel B. The respective weights of the water filled in vessels are W A and W B. Then

(A) FA > FB ; W A > W B (C) FA = FB ; W A < W B

(B) FA = FB ; W A > W B (D) FA > FB ; W A = W B

3.

In a hydraulic lift, used at a service station the radius of the large and small piston are in the ratio of 20: 1. What weight placed on the small piston will be sufficient to lift a car of mass 1500 kg ? (A) 3.75 kg (B) 37.5 kg (C) 7.5 kg (D) 75 kg.

4.

An iceberg is floating in ocean. What fraction of its volume is above the water ? (Given : density of ice = 900 kg/m3 and density of ocean water = 1030 kg / m3) (A) 90 / 103 (B) 13 / 103 (C) 10 / 103 (D) 1 / 103

5.

A block of wood is floating on oil with half of its volume submerged. If the density of oil 840 kg m–3, the relative density of wood (relative to water) is: (A) 0.84 (B) 0.42 (C) 0.21 (D) 1.00

6.

The pressure at the bottom of the four vessels filled with water to the same level is P1, P2, P3 and P4 respectively. Then which of the following conclusion is correct.

P1 (A) P1 > P2 > P3 > P4

P2 (B) P1 < P2 < P3 P3

(D) P1 = P2 = P3 =P4

7.

A bucket tied to a string is lowered at a constant acceleration of g/4. If the mass of the bucket is M and is lowered by a distance d, the work done by the string on bucket will be (assume the string to be massless) (A) –3/4 mg d (B) – 7/5 mg d (C) – 2mg d (D) – 4mg d

8.

A loaded bus (mass m2 ) and an unloaded bus (mass m1) are both moving with the same kinetic energy. Brakes are applied to both the buses so as to exert equal retarding force. If s1 and s2 are the distances

s1 covered by the two buses respectively, before coming to rest, then s is : 2

(A) 1. 9.

m1 (B) m 2

(C)

m1 m2

2

(D)

m1

m2 2

If the frequency of a wave is increased by 25 %, then find the change in its wavelength. (medium not changed) (A) 30%

10.

(B) 10%

(C) 25%

(D) 20%

Consider two spherical planets of same average density. Planet 2 is 8 times as massive as planet 1. The ratio of the accelertion due to gravity of the second planet to that of the first is. (A) 1 (B) 2 (C) 4 (D) 8

11.

If both the mass and the radius of the earth decreases by 1%, then : (A) the escape velocity would increase by 1% (B) the acceleration due to gravity would increase by 1% (C) the escape velocity would decrease by 1% (D) the acceleration due to gravity would decrease 1%

12.

A ship of mass 3 × 107 kg initially at rest is pulled by a force of 5 × 104 N through a distance of 3m. Assume that the resistance due to water is negligible, the speed of the ship is : (A) 1.5 m/s (B) 60 m/s (C) 0.1 m/s (D) 5 m/s

13.

When a horse pulls a cart, the force needed to move the horse in forward direction is the force exerted by : (A) The cart on the horse (B) The ground on the horse (C) The ground on the cart (D) The horse on the ground

14.

A particle of mass m1 moving with velocity v collides with a mass m2 at rest, then they get embedded. Just after collision, velocity of the system : (A) Increases (B) Decreases (C) remains constant (D) becomes zero

15.

One end of string which passes through pulley and connected to 10 kg mass at other end is pulled by 100 N force. Find out the acceleration of 10 kg mass. (g =9.8 m/s2)

(A) 1.2 m/s2.

(B) 0.5 m/s2.

(C) 1.3 m/s2.

(D) 0.2 m/s2.