# Rotational dynamics mcqs with answers pdf

1. The moment of inertia of a body does not depend upon the________

(a) mass of the body

(b) position of the axis of rotation

(c) distribution of the mass

(d) the angular acceleration of the body

2. The SI unit of moment of inertia is________

(a) gram-cm²

(b) kg-m²

(c) kg/m²

(d) kg-m

3. The dimensional formula for moment of inertia of a body is______

(a) L⁰M¹T-²

(b) L²M¹T⁰

(c) L¹M¹T-¹

(d) L⁰M²T-¹

4. The dimensional formula for the radius of gyration of a body is______

(a) L⁰M⁰T⁰

(b) L¹M⁰T⁰

(c) L¹M¹T⁰

(d) L⁰M²T-¹

5. The SI unit of torque is_______

(a) N/m

(b) Nm²

(c) N-m

(d) N²m

6. Which is the axial vector from the following?

(a) Linear Momentum

(b) Torque

(c) Velocity

(d) Acceleration

7. The rotational analogue of force is_________

(a) Moment of Inertia

(b) Angular Momentum

(c) Torque

(d) Angular Acceleration

8. The physical quantity in translational motion, which analogous to torque in rotational motion is________

(a) Mass

(b) Linear Momentum

(c) Force

(d) Work

9. Torque per unit moment of inertia is________

(b) Angular velocity

(c) Angular displacement

(d) Angular acceleration

10. The physical quantity in translational motion, which is analogous to moment of inertia in rotational motion is________

(a) Velocity

(b) Force

(c) Energy

(d) Mass

11. Moment of inertia depends upon________

(a) position of axis of rotation

(b) distribution of particles

(c) mass

(d) all of these

12. If all the ice on the polar caps of the earth melts, due to global warming then the duration of the day will be________

(a) 24 hours

(b) more than 24 hours

(c) less than 24 hours

(d) 12 hours

13. Which of the following types of circular bodies, Same mass and radius will have the largest moment of inertia ?

(a) Solid disc

(b) Cylindrical disc

(c) Ring

(d) Annular disc

14. A flywheel rotating about a fixed axis has a kinetic energy of 225 J when its angular speed is 30 rad/s. What is the moment of inertia of the flywheel about its axis of rotation?

(a) 0.5 kg m²

(b) 0.6 kg m²

(c) 0.8 kg m²

(d) 0.3 kg m²

15. The mass of a flywheel is concentrated near its rim. This is done to_______

(a) decrease its moment of inertia

(b) increase its moment of inertia

(c) increase the strength of the flywheel

(d) increase its linear momentum

16. A wheel of mass 4 kg and radius of gyration 0.4 m is making 300 r.p.m. Its moment of inertia is_______

(a) 6.4 kg m²

(b) 0.64 kg m²

(c) 0.32 kg m²

(d) 64 kg m²

17. Two circular rings A and B of radii nR and R are made from the same wire. The M.I. of A about an axis passing through the centre and perpendicular to the plane of A is 27 times that of the smaller loop B. What is the value of n?

(a) 2

(b) 3

(c) 4

(d) 5

18. When the speed of a flywheel is increased from 240 r.p.m. to 360 r.p.m., the energy spent is 484 J. What is the moment of inertia of the flywheel ?

(a) 4.9 kg-m²

(c) 2 kg-m²

(b) 9.8 kg-m²

(d) 15 kg-m²

19. A torque of 100 N-m acting on a wheel at rest, rotates it through 200 radian in 10s. What is the moment of inertia of the wheel?

(a) 10 kg-m²

(b) 15 kg-m²

(c) 20 kg-m²

(d) 25 kg-m²

20. If  the external torque acting on a body is zero, then its______

(a) angular momentum is zero

(b) angular momentum is conserved

(c) angular momentum is maximum

(d) angular acceleration is maximum

21. When the external torque acting on a system is zero, then there will be conservation of______

(a) total energy

(b) angular momentum

(c) linear momentum

(d) mass

22. When a torque acting on a system is increased, then which one of the following quantities will increases.

(a) linear momentum

(b) Angular momentum

(c) force

(d) Displacement

23. The moment of inertia of a copper disc, rotating about an axis passing through its centre and perpendicular to its plane_______

(a) increases if its temperature is increased

(b) changes if its axis of rotation is changed

(c) increases if its angular velocity is increased

(d) both (a) and (b) are correct

24. when a steady torque acts on a body, the body_______

(a) rotates at a constant speed

(b) continues in its state of rest or of uniform motion along a straight line

(c) gets a linear acceleration

(d) gets an angular acceleration

25. Moment of inertia of a body is considered only in the case of_________

(a) Rectilinear motion

(b) Rotational motion

(c) Curvilinear motion

(d) Translational motion

26. When the external torque acting on a rotating body is zero, the quantity that will remain constant is the_________

(a) linear momentum

(b) angular momentum

(c) force

(d) linear displacement

27. Which is the wrong relation from the following?

(a) Force = Mass x Acceleration

(b) Torque = Moment of Inertia x Angular Acceleration

(c) Moment of Inertia = Torque x Angular Acceleration

(d) Angular Momentum = Moment of Inertia x Angular Velocity