Work, Energy, and Power Mock Test – Class 11 Physics

1. The relation between kilowatt-hour and joule is

2. Use the graph description below.

The allowed region of motion is

3. A body of mass moves with speed at height . Taking and choosing ground as , its total mechanical energy is

4. Read the case below and answer the question.

For the work done by gravity, the best conclusion is that

5. A object at rest separates into two fragments of masses and . If the fragment has speed , the total kinetic energy after separation is

6. In a head-on collision, the relation is used along with momentum conservation because

7. The dimensions of work and energy are obtained from force multiplied by displacement. The dimensional formula is

8. On a graph of power versus time , the area under the graph represents

9. The following statements refer to oblique collision with a fixed smooth wall.
I. The velocity component normal to the wall is affected by the collision.
II. The velocity component parallel to the wall remains unchanged for a smooth wall.
III. In an elastic collision, the speed remains unchanged.
IV. In an elastic collision, both components must become zero.
The true statements are

10. A cart moving at collides head-on with a cart initially at rest. If , the final velocities are

11. Potential energy associated with a force is meaningfully defined when the force is

12. Two bodies collide elastically in one dimension. Their initial velocities are and , and their final velocities are and . A useful relative-velocity relation for an elastic collision is

13. A spring-block system has , , and amplitude on a smooth horizontal surface. The maximum speed of the block is

14. A moving system breaks apart without external impulse. The centre-of-mass velocity after the break-up is

15. Two statements about net work are given.
I. Net work can be found by adding the work done by each force with signs.
II. Net work can also be found from the work done by the resultant force over the same displacement.
III. Net work is always equal to the sum of force magnitudes multiplied by distance.
The true statements are

16. A body moving at sticks to a body moving at . The common final velocity is

17. A box is moved from the floor to a table high and then to a shelf high. Taking , the increase in gravitational potential energy from the table to the shelf is

18. A force remains perpendicular to the velocity of a moving particle at every instant. The instantaneous power of that force is

19. A body starts from rest under a variable net force. The area under its graph from to is . If the mass is , its speed at is

20. In a one-dimensional elastic collision, the two conservation equations used together are

21. A net force acts on a body and does zero net work over a displacement. The work-energy theorem implies that

22. A body has kinetic energy . Taking , its kinetic energy in joule is

23. Study the table for a body moving vertically near Earth's surface.

The row with the wrong sign is

24. Study the table for a separation event with negligible external impulse.

The row that needs correction is

25. A ball strikes a fixed wall normally with speed . If the coefficient of restitution is , the speed of rebound is

26. A person pushes a box with a force of at an angle such that the component along the displacement is . If the box moves , the work done by the pushing force is

27. A machine is efficient. To deliver of useful work, the input energy required is

28. A body has initial kinetic energy . The net work done on it is . Its final kinetic energy is

29. A body of mass starts from rest at . The net force acting along the -axis is , where is in and is in . Its speed at is

30. Read the case below and answer the question.

The speed of the bead at Q is

31. A ball is dropped from height onto a fixed horizontal floor. If the coefficient of restitution is , the height reached after the second rebound is

32. A car engine supplies constant power while the car moves faster on a level road. If the useful driving power is , the driving force available at higher speed is

33. A ball is dropped from and rebounds from a fixed floor with . Taking , the kinetic energy just after the first rebound is

34. Read the case below and answer the question.

For the work done by gravity, the best conclusion is

35. A student solves a collision problem by conserving mechanical energy even though the bodies stick together after impact. The main issue is that

36. A smooth ball hits a fixed wall obliquely. If the wall is vertical and smooth, and the collision is elastic, the component of velocity parallel to the wall

37. A pendulum bob rises from the lowest point to a height above it. Neglecting air resistance, the speed it must have at the lowest point to just reach that height is

38. A system initially at rest separates into two fragments. The lighter fragment has one-third the mass of the heavier fragment. The kinetic energy of the lighter fragment compared with the heavier fragment is

39. A spring has . It is stretched from to . The work done by the spring force is

40. A ball collides elastically with a fixed wall. Which quantity of the ball changes during the collision?

41. A body of mass moving with speed sticks to an identical body initially at rest. Which statement about momentum and kinetic energy is correct?

42. A block moves on a rough horizontal surface with initial speed . Friction does of work. What is the final speed?

43. A block moving at compresses a spring of constant on a rough horizontal surface. Friction does of work before maximum compression. The maximum compression is

44. During horizontal motion of a block, three forces act: an applied force along motion, friction opposite motion, and weight vertically downward. Their work signs are respectively

45. A machine lifts water with useful output power . If its efficiency is , the rate at which energy is wasted is

46. A ball has velocity components normal to a smooth fixed wall and parallel to the wall before impact. If , its speed just after collision is

47. Two carts collide on a frictionless horizontal track and stick together after impact. This collision is

48. A body moving at collides with a stationary body. If the collision is perfectly elastic and head-on, the final velocities are

49. The following statements refer to collisions.
I. Momentum is conserved in an isolated collision.
II. Kinetic energy is conserved in every collision.
III. In a perfectly inelastic collision, bodies stick together after collision.
IV. In an elastic collision, total kinetic energy is conserved.
The true statements are

50. Two balls of different masses are dropped from the same height in vacuum. The reason they reach the ground with the same speed is that