Multiple choice questions of Chapter 5 of Physics for First Year.

## CHAPTER # 5: CIRCULAR MOTION

1. The rate of change of angular displacement is called:
a) Angular displacement
b) Angular velocity
c) Angular acceleration
d) Torque

2. Revolution/minute is the unit for
a) Angular displacement
b) Angular acceleration
c) Angular velocity
d) Time

3. Time rate of change of angular velocity is called:
a) Angular momentum
b) Angular displacement
c) Angular acceleration
d) None of these

4. The angular acceleration is produced by:
a) Momentum
b) Torque
c) Pressure
d) Power

5. A particle is moving in a circle with constant speed. The direction of centripetal force will be:
a) Along the tangent
c) Along radius away from center
d) Changing with motion

6. The direction of linear velocity of body moving in a circle is.
a) Along the axis of rotation
b) Along the tangent
c) Directed towards the center
d) Directed away from the center

7. The circumference subtends an angle.

8. When a body is whirled in a horizontal circle by means of a string the centripetal force is supplied by.
a) Mass of a body
b) Velocity of body
c) Tension in the string
d) None of these

9. Centripetal force performs
a) Maximum work
b) Minimum work
c) Negative work
d) No work

10. The angular acceleration of a body is directed
a) Towards the center of the circle
b) Away from the center of the circle
c) Along the tangent to the circle
d) Along the axis of rotation

11. A gymnast sitting on stool with his arms out stretched lowers his arms:
a) The angular speed decreases
b) The angular speed increases
c) Neither increases nor decrease
d) Both increases and decreases

12. When torque acting on a system is zero, which of the following will be constant:
a) Linear momentum
b) Force
c) Angular momentum
d) Impulse

13. The apparent weight of a man in an ascending lift moving with acceleration “a”:
a) Increases
b) Decreases
c) Remains constant
d) Becomes zero

14. The apparent weight of a man in a lift moving down with an acceleration of 9.8 𝑚 𝑠 ^−2 is:
a) Zero
b) 9.8 N
c) 19.6 N
d) Infinity

15. Which electromagnetic wave are used as medium in satellite communication system:
a) Microwaves
c) Infrared waves
d) Ultraviolet waves

16. The minimum number of communication satellites required to cover the whole earth is:
a) 4
b) 3
c) 2
d) 5

17. Geo-stationary satellite completes one rotation around earth in.
a) 3 hours
b) 6 hours
c) 12 hours
d) 24 hours

18. In case planets the necessary acceleration is provided by.
a) Gravitational force
b) Frictional force
c) Coulomb force
d) Centripetal force

19. A man of weight W is standing on an elevator which is ascending with an acceleration a. The apparent weight of the man is.
a) mg
b) mg – ma
c) mg + ma
d) mg – ma

20. If a body of mass 10 kg is allowed to fall freely, its weight becomes.
a) zero
b) 98N
c) 9.8N
d) 10N

21. Pull of earth on a mass of 20 kg on the surface of the earth is
a) 20 N
b) 196 N
c) 19.6 N
d) 1960 N