CBSE - Physics - Motion

1. A particle is moving in a circular path of radius r. The displacement after half a
circle would be:
(a) Zero
(b) πr
(c) 2r
(d) 2πr
Ans. (c) 2r
Explanation: After half a circle, the particle will be diametrically opposite to its origin.
Hence, displacement is equal to diameter.

2. A body is thrown vertically upward with velocity u, the greatest height h to which it
will rise is,
(a) u/g
(b) u2/2g
(c) u2/g
(d) u/2g
Ans. (b) u2/2g
3. The numerical ratio of displacement to distance for a moving object is
(a) always less than 1
(b) always equal to 1
(c) always more than 1
(d) equal or less than 1
Ans. (d) equal or less than 1
Explanation: Displacement can be equal or less than distance but it will never be more than distance.

4. If the displacement of an object is proportional to square of time, then the object moves with
(a) uniform velocity
(b) uniform acceleration
(c) increasing acceleration
(d) decreasing acceleration
Ans. (b) uniform acceleration
Explanation: Velocity is measured in terms of distance per second, while acceleration is measured in terms of distance per square second.
Hence, uniform acceleration is the correct answer.

5. From the given v � t graph (Fig. 8.1), it can be inferred that the object is


(a) in uniform motion
(b) at rest
(c) in non-uniform motion
(d) moving with uniform acceleration
Ans. (a) in uniform motion
Explanation: Straight horizontal line which is above zero on x-axis; shows uniform motion.

6. Suppose a boy is enjoying a ride on a merry-go-round which is moving with a constant speed of 10 ms^�1. It implies that the boy is
(a) at rest
(b) moving with no acceleration
(c) in accelerated motion
(d) moving with uniform velocity

Ans. (c) in accelerated motion
Explanation: A boy on a merry-go-around is in circular motion. Circular motion is an example of acceleration motion.

7. Area under a  v � t graph represents a physical quantity which has the unit
(a) m2
(b) m
(c) m3
(d) ms�1
Ans. (b) m
Explanation: The given area represents displacement. Unit of displacement is meter.

8. Four cars A, B, C and D are moving on a levelled road. Their distance versus time graphs are shown in Fig. 8.2. Choose the correct statement
(a) Car A is faster than car D.
(b) Car B is the slowest.
(c) Car D is faster than car C.
(d) Car C is the slowest.
Ans. (b) Car B is the slowest.
Explanation: Graph for car B attains least height (on x-axis) in the given time. Hence, it is the slowest car

9. Which of the following figures (Fig. 8.3) represents uniform motion of a moving object correctly?






Ans. (a)
Explanation: Distance is increasing at a uniform rate; as shown by upward slanting
straight line. Hence, this graph shows uniform motion.
10. Slope of a velocity � time graph gives
(a) the distance
(b) the displacement
(c) the acceleration
(d) the speed
Ans. (c) the acceleration

11. In which of the following cases of motions, the distance moved and the magnitude of displacement are equal?
(a) If the car is moving on straight road
(b) If the car is moving in circular path
(c) The pendulum is moving to and fro
(d) The earth is revolving around the Sun
Ans. (a) If the car is moving on straight road
Explanation: In all other class, displacement can be less than distance.