System of Particles and Rotational Motion Mock Test – Class 11 Physics

1. The condition for translational equilibrium of a rigid body is

2. If no external torque acts on a rotating body and its moment of inertia decreases, its angular speed

3. Study the table and identify the row that correctly describes for fixed non-zero and .

4. A plane lamina has and about two perpendicular axes in its plane through the same point. Its moment of inertia about the perpendicular axis through that point is

5. Assertion: A hoop rolling down an incline has smaller acceleration than a solid cylinder rolling down the same incline without slipping.
Reason: The hoop has a larger value of than the solid cylinder.

6. A student says, "If a particle has constant angular momentum, no force can be acting on it." The best correction is that

7. The centre of mass is especially useful in system mechanics because it

8. Match each situation with the most suitable centre-of-mass idea.

9. Use the graph description below.

The slope of this graph is

10. The relation between torque and angular momentum for a particle is

11. A compound wheel has two coaxial parts. A force acts tangentially at radius , while another equal force acts tangentially in the opposite rotational sense at radius . The net torque magnitude is

12. A uniform solid cylinder rolls without slipping with centre-of-mass speed . If , its total kinetic energy is

13. Use the arrangement described below. Two blocks are connected by a light string and pulled on a smooth table. If both blocks together are chosen as the system, the tension in the string is

14. A two-particle system has masses and at positions and . If both masses are doubled while their positions remain unchanged, will

15. A system boundary is chosen around two carts connected by a compressed spring. If both carts are included in the system, the spring forces between the carts are classified as

16. A solid sphere of mass and radius rolls without slipping towards the right with centre-of-mass speed . Find the magnitude and direction of its angular momentum about the instantaneous point of contact with the ground. Take .

17. A uniform wire is bent into a shape but its mass per unit length remains constant everywhere. While setting up its centre-of-mass calculation, the most important local element is

18. In pure rolling, the total kinetic energy may be written as . For a solid sphere, . Then is

19. Two particles of masses and are separated by . A claim says, "The centre of mass is almost at the particle, so the lighter particle can be ignored completely." The best response is that the claim is

20. Match the vector-pair condition with the cross-product result.

21. A system has momentum changing from to in . The average external force on the system is

22. A uniform disc of mass and radius has centre-of-mass velocity towards the right. At the same instant, it has angular speed clockwise. The point is on the ground directly below the centre of the disc. Find the angular momentum of the disc about . Take .

23. A data-processing error replaces by while finding . The result is physically unacceptable mainly because

24. In rolling without slipping, the condition is valid only when is measured in

25. A constant torque of acts on a wheel through an angular displacement of . The work done by the torque is

26. A pair of equal and opposite parallel forces acting at different points on a rigid body forms a couple. The main effect of a couple is to produce

27. The SI unit of torque is

28. Two particles of masses and move along the -axis with velocities and , respectively. The velocity of the centre of mass is

29. Two particles inside a system exert equal and opposite forces on each other along the same line. In the equation for the whole system, these two forces

30. A vector lies in the plane of a page toward the right, and lies in the same plane upward. The direction of is

31. For a system of particles, the moment of inertia about an axis is given by

32. A rigid body rotates with angular acceleration . The tangential acceleration of a point at distance from the axis is

33. In a two-dimensional torque problem, a positive torque is usually assigned to anticlockwise rotation. This sign convention is useful because it

34. A solid cylinder of mass and radius lies on a rough horizontal surface. A horizontal force of is applied through its centre towards the right. The cylinder rolls without slipping. If , what are the acceleration of its centre and the direction of static friction?

35. A solid cylinder rolls without slipping down an incline. The frictional force on it acts up the incline. Its role is mainly to

36. A non-uniform rod is thicker and heavier near its left end. Its geometrical midpoint and centre of mass are compared. The centre of mass is expected to be

37. A solid sphere rolls without slipping with speed . Given , its total kinetic energy is

38. A graph compares acceleration down the same incline for rolling bodies with different values of , where . As increases, the graph should show

39. A system has two particles of mass at and , and a third particle of mass at . Its centre of mass is

40. Study the table and choose the row that correctly describes pure rolling down an incline from rest.

41. The torque of a couple is independent of the chosen origin because

42. The value of is

43. A rigid body rotates about a fixed axis. All particles of the body have the same

44. A particle moves in a circle about the origin under a force directed toward the origin. Its angular momentum about the origin is conserved because

45. A uniform horizontal beam of length and mass is hinged at its left end. A cable attached to the right end makes an angle of above the beam. A load is hung at a point from the hinge. If , find the cable tension and the vertical reaction at the hinge.

46. The magnitude of torque is

47. The determinant method for is useful mainly because

48. A wheel of radius rolls without slipping. Its centre has acceleration . The angular acceleration of the wheel is

49. A composite body is made by joining two point-replaceable parts. Part P has mass and its own centre at . Part Q has mass and its own centre at . The centre of mass of the composite body is

50. A wheel rotates with angular speed . At a rim point, the centripetal acceleration is . If is tripled while the radius is unchanged, becomes