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

1. Study the work record for a body moving along a straight line.

The net work on the body is

2. A force is tested by moving a body between the same two points along different paths. If the measured work is different for different paths, the force is

3. The following final statements about work, energy, power, and collisions are given.
I. Work done by a force is linked with the component of force along displacement.
II. Power describes the rate of doing work or transferring energy.
III. In an isolated collision, momentum is conserved even when kinetic energy is not.
IV. Mechanical energy is always conserved in the presence of kinetic friction.
The true statements are

4. A two-body isolated collision has initial kinetic energy . After collision, the total kinetic energy is . The value of is

5. The coefficient of restitution for a head-on collision is defined as

6. A block moves along a straight line, and the net work done on it is known. From the work-energy theorem alone, one can directly find

7. The relation means that one joule is the work done when

8. A stone is lowered slowly from a shelf to the floor. During this process, the work done by gravity and the change in gravitational potential energy are respectively

9. Assertion: A particle placed exactly at a local maximum of can be in equilibrium.
Reason: At a local maximum, the slope of graph is zero.

10. 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

11. 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

12. A force-displacement record for a body is shown.

If the initial kinetic energy is , the final kinetic energy is

13. 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

14. A block of mass moving at is acted on by a constant net force along its motion through . If the force is , its final speed is

15. Work and energy are treated as scalar quantities in elementary mechanics. This means that their values

16. A force of acts on a particle moving with speed . The force makes an angle of with the velocity. The instantaneous power is

17. 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

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

19. A friction force acts on a sliding object over a closed rough path of total length . The object returns to its starting point. The work done by friction is

20. A curve has a local maximum at . A particle placed exactly at with zero speed is in

21. Read the situation below and answer the question.

The rate of change of the cart's kinetic energy at that instant is

22. A spring-block system on a smooth horizontal surface has total mechanical energy . At a certain instant, the spring potential energy is . The block's kinetic energy is

23. A body of mass changes speed from to . The net work done on it can be written as

24. The electron-volt is a unit of

25. A block, spring, rough surface, and collision are used in one experiment. The block is first released from a compressed spring, then slides across a rough surface, and finally sticks to another block. The safest sequence of principles is

26. A spring is stretched from to . The work done by the spring force during this process is

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

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

29. A particle is in equilibrium at a point on a graph when

30. A particle is acted on by a force whose power varies with time. The power is for , then for . The net change in the particle's mechanical energy due to this force is

31. Two motors lift the same load through the same height. Motor P takes , while motor Q takes . The ratio of their average powers is

32. A body of mass moves from height to height . The change in gravitational potential energy is

33. Read the case below and answer the question.

The speed of the bead at Q is

34. The following statements refer to work by common forces.
I. Normal reaction does zero work whenever it is perpendicular to displacement.
II. Kinetic friction usually does negative work during sliding.
III. Tension always does zero work in every string problem.
IV. Static friction may do positive, negative, or zero work depending on the situation.
The true statements are

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

36. Two identical balls move toward each other with velocities and . They collide elastically in one dimension. The final velocities are

37. The following statements are about the work-energy theorem.
I. It uses net work, not necessarily the work of a single chosen force.
II. Positive net work increases kinetic energy.
III. Zero net work always means the body is at rest.
IV. Negative net work decreases kinetic energy.
The true statements are

38. A particle of mass has total mechanical energy . At a point where , its speed is

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

40. A lamp is rated . The energy it consumes in is

41. A claim says, "If total mechanical energy is conserved, kinetic energy must be constant." The best correction is that

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

43. Two reference levels are chosen for the same raised object. In choice P, the ground is assigned . In choice Q, the table top is assigned . The physically meaningful result that remains the same is

44. The angle between a constant force and displacement is changed from to , while and remain unchanged. The work done becomes

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

46. A ball moving at makes a head-on elastic collision with an identical ball initially at rest. After collision, the first ball comes to rest. The speed of the second ball is

47. A car moving on a road is brought to rest by braking. In a simple mechanical description, the brakes and road forces reduce the car's

48. A object is raised from to above the floor. Taking , the change in gravitational potential energy is

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

50. A force is called non-conservative when the work done by it between two points