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

1. A motor does of work in . What is its average power?

2. Use the arrangement described below: a light string passes over a smooth pulley, connecting block P on a horizontal table to hanging block Q. As Q moves downward, P moves horizontally toward the pulley. Ignoring friction, how is the work done by tension on the two blocks classified?

3. The work-energy theorem states that the net work done on a body is equal to

4. Near Earth's surface, if the zero of gravitational potential energy is chosen at , the gravitational potential energy at height is

5. A body moves from to . The net work done on the body is

6. A spring is stretched slowly from its natural length by . If , the work done by the external agent is

7. A block attached to a spring is pulled slowly from the natural position to . The spring constant is . The final spring force magnitude and the external work done are respectively

8. A body moves from a point where and to another point where . If no non-conservative work is done, its speed at the second point is

9. A small cart and a large cart have equal kinetic energies. The large cart has greater momentum magnitude. This is consistent with

10. 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

11. A particle of mass moves in a potential-energy field with total energy . At position P, ; at position Q, . The speed is greater at

12. A ball falls freely through a vertical height of . If its mass is , what is the work done by gravity? Take .

13. Study the table about conservative and non-conservative work.

The row that needs correction is

14. A student reads an graph and says, "The largest force value must be multiplied by the whole displacement to get work." The best response is that this method

15. For a force acting along the -axis, a negative value of means that

16. The expression shows that work is a

17. Match the mechanical energy terms with their most suitable descriptions.

18. Assertion: The work done by a force perpendicular to displacement is zero.
Reason: In , .

19. A pump lifts of energy in . Its average power is

20. Two machines lift identical loads through the same vertical height, but machine completes the task in less time than machine . The quantity that is definitely greater for machine is

21. Study the table about an ideal spring.

The row that needs correction is

22. For a body moving near Earth's surface, the relation between work done by gravity and change in gravitational potential energy is

23. A point on a potential energy curve is called a turning point of the motion when

24. A body is moved around a closed rough track and returns to its starting point. The work done by kinetic friction over the complete trip is generally

25. A block of mass starts from rest at height and slides down a rough track. At the bottom its speed is . Taking , the work done by friction is

26. Two forces act on a box while it moves in a straight line. Force does of work and force does of work. The net work done on the box is

27. A body is moved between two points. Gravity does of work, while friction does of work. The change in kinetic energy is

28. A cart moving at collides elastically with a stationary cart on a straight frictionless track. The final velocity of the cart is

29. 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

30. Study the table about machine efficiency.

The row that is physically unsuitable for an ordinary passive machine is

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

32. A final integrated record is shown below.

The row that needs correction is

33. The same ideal spring is compressed by in one case and stretched by in another case. The elastic potential energy stored in the spring is

34. A stationary object separates into two parts. Part P has mass , and part Q has mass . If part P moves with speed , the speed of part Q is

35. A graph of potential energy has a local minimum at . A particle with total energy slightly above is placed near . Its motion near is best described as

36. A collision is described as isolated and perfectly inelastic. Which pair of statements is correct?

37. A moving hammer strikes a nail and drives it into wood. In the work-energy description, the hammer mainly uses its

38. In a region where the graph is perfectly horizontal, the force on the particle is

39. A collision record shows that the total momentum before and after collision is the same, but the final kinetic energy is smaller than the initial kinetic energy. The collision is best classified as

40. A body has initial speed . During its motion, the signed area under the graph is . Its final speed is

41. A machine receives input energy at the rate and delivers useful output energy at the rate . The efficiency of the machine is

42. Study the table about mechanical energy conservation.

The row that needs correction is

43. A potential energy function is , where is in and is in . The equilibrium position is

44. A body is moving to the right. A net force to the left acts on it for some displacement to the right. According to the work-energy theorem, the body's kinetic energy

45. A motor does the same work in half the time. Its average power becomes

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

47. A force of magnitude acts on a body while the displacement has magnitude . The displacement component along the force is . A valid expression for work is therefore

48. 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

49. A lift carries a total mass of upward at constant speed . If , the minimum motor power needed to lift it is

50. In a one-dimensional comparison, body P has mass and speed , while body Q has mass and speed . Their momenta and kinetic energies compare as