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

1. 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

2. A spring is taken from extension to extension . The work done by the spring force is

3. Match the force type with the correct work property.

4. 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

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

6. A graph of versus for a moving body has a positive area of followed by a negative area of . The change in kinetic energy over the whole interval is

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

8. 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

9. A box slides on a smooth horizontal floor. The normal reaction on the box is . The work done by the normal reaction is

10. A smooth vertical motion problem is solved by two students using different zero levels for gravitational potential energy. If both use energy conservation consistently, their calculated speed at a given height will be

11. A spring force acts on a block attached to a horizontal spring. The block moves from to . The work done by the spring is positive because

12. 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

13. The following statements refer to potential energy.
I. It is associated with configuration or position for conservative forces.
II. Its change satisfies .
III. Its zero level may be chosen conveniently.
IV. Only the absolute value of is physically meaningful, never the difference.
The true statements are

14. Use the graph description below.

The work done by the external force in stretching the spring from to is represented by

15. 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?

16. A body of mass slows from speed to rest because of a constant resistive force. The magnitude of net work done by the resistive force is

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

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

19. Mechanical work by a constant force is best described by the relation

20. A body has kinetic energy . Its momentum magnitude is

21. Read the situation below and answer the question.

If the forward motor work is larger than the backward resistive work in magnitude, the net work on the trolley is

22. A ball moves from point P to point Q near Earth's surface. Point Q is lower than point P. If the mass is and , the work done by gravity is

23. A cart moving at collides elastically with an identical cart moving at in the same direction. What are the final velocities in the same order?

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

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

26. A constant force and displacement are described as follows.

The row that does not match the sign of work is

27. Assertion: Kinetic energy of a moving body can never be negative.
Reason: Kinetic energy is proportional to the square of speed.

28. A compressed spring pushes a toy car forward on a smooth horizontal surface. The main energy transformation is

29. Mechanical energy of a system is commonly written as

30. A car moves with constant useful engine power on a level road where resistive force is negligible for a short interval. If its speed increases, the acceleration

31. A device has constant power for . The energy transferred is represented by the area under its graph. The energy transferred is

32. A lighter body and a heavier body have equal momentum magnitudes. The lighter body has greater kinetic energy because

33. Study the collision records below.

The row that needs correction is

34. A book is lifted from a table to a shelf. The gravitational force does of work during the lift. The change in gravitational potential energy is

35. A object moving at sticks to a object moving at . A different event starts with the same two objects at rest and releases a spring between them. The key difference is that

36. A graph has these features: from point P to point Q, decreases steadily; from Q to R, is constant; from R to S, increases steadily. For a particle moving under this conservative force, the force direction is best described as

37. Read the case below and answer the question.

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

38. Study the table for a curve.

The row that needs correction is

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

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

41. The following statements compare energy and momentum in collisions and separations.
I. Total momentum is conserved when external impulse is negligible.
II. Total kinetic energy is conserved only in elastic collisions, not in all collisions.
III. In an explosion from rest into two parts, the momenta are equal and opposite.
IV. In a perfectly inelastic collision, the bodies move together after impact.
The true statements are

42. A crate is pushed across a rough horizontal floor. The applied force does of work, while friction does of work. If the crate starts from rest and has mass , its final speed is

43. A table gives total kinetic energy before and after collisions of isolated two-body systems.

The row that needs correction is

44. Net work is calculated by adding individual works algebraically because work is

45. A projectile of mass is launched with speed at an angle above the horizontal. Neglecting air resistance, the maximum height is found from the vertical component of kinetic energy as

46. A ball is dropped from height and rebounds repeatedly from a fixed floor with coefficient of restitution . The ratio of the height after the third rebound to the original height is

47. Read the situation below and answer the question.

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

48. A body and a body have the same kinetic energy. The ratio of their speeds is

49. 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

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