Kinetic and potential energy and work–energy theorem - Question Bank

1. Which quantity is conserved when a body moves under a conservative force and no external forces act on it?
A) Kinetic energy
B) Potential energy
C) Total mechanical energy
D) Momentum
2. The work done by a non-conservative force like friction:
A) Is always zero
B) Is always positive
C) Is always negative
D) Can be positive or negative depending on the situation
3. A 5 kg object is moving with a velocity of 2 m/s. If its velocity increases to 4 m/s, the change in its kinetic energy is:
A) 10 J
B) 20 J
C) 30 J
D) 40 J
4. If a force does negative work on an object, the object's kinetic energy:
A) Increases
B) Decreases
C) Stays the same
D) Becomes zero
5. The work done by gravity when an object falls from height h to the ground is:
A) -mgh
B) mgh
C) 0
D) 1/2 mgh
6. A 2 kg object is at rest. A net force of 4 N acts on it for 3 seconds. What is its kinetic energy at the end of 3 seconds?
A) 18 J
B) 36 J
C) 72 J
D) 144 J
7. If an object's kinetic energy is K, and its mass is m, what is its momentum p?
A) sqrt(2mK)
B) sqrt(mK/2)
C) 2mK
D) mK
8. The work-energy theorem is particularly useful for problems involving:
A) Constant velocity
B) Constant acceleration
C) Variable forces
D) Static equilibrium
9. Kinetic energy is a form of energy associated with:
A) Position
B) Temperature
C) Motion
D) Chemical bonds
10. Potential energy is a form of energy associated with:
A) Motion
B) Position
C) Heat
D) Light
11. A 0.5 kg object is moving at 10 m/s. If a force does 20 J of work on it, its new velocity will be approximately:
A) 10 m/s
B) 12.4 m/s
C) 14.1 m/s
D) 15.8 m/s
12. Which of the following statements is true about work done?
A) Work done is always positive.
B) Work done is always negative.
C) Work done can be positive, negative, or zero.
D) Work done is a vector quantity.
13. If a force is applied at an angle θ to the direction of displacement, the work done is:
A) Fd cos θ
B) Fd sin θ
C) Fd tan θ
D) Fd
14. The potential energy of a spring is given by:
A) kx
B) 1/2 kx
C) kx^2
D) 1/2 kx^2
15. If the mass of an object is doubled and its velocity is halved, its kinetic energy will be:
A) Halved
B) Doubled
C) Same
D) Quadrupled
16. What is the work done by the centripetal force in circular motion?
A) Positive
B) Negative
C) Zero
D) Depends on speed
17. When a body falls freely under gravity, its total mechanical energy:
A) Increases
B) Decreases
C) Remains constant
D) First increases then decreases
18. A 10 kg object is at a height of 5 m. Its potential energy is (g = 10 m/s^2):
A) 50 J
B) 100 J
C) 500 J
D) 1000 J
19. What is the change in potential energy when an object of mass 'm' is raised from height h1 to h2?
A) mg(h2 - h1)
B) mg(h1 - h2)
C) mgh1
D) mgh2
20. A force of 5 N acts on a particle of mass 1 kg. If the particle starts from rest, its kinetic energy after 10 seconds will be:
A) 250 J
B) 500 J
C) 1250 J
D) 2500 J
21. If the speed of an object decreases, its kinetic energy:
A) Increases
B) Decreases
C) Remains the same
D) Becomes zero
22. The work-energy theorem is a direct consequence of:
A) Newton's first law
B) Newton's second law
C) Newton's third law
D) Conservation of energy
23. Which of the following is an example of kinetic energy?
A) Water stored in a dam
B) A stretched rubber band
C) A flying airplane
D) A compressed gas cylinder
24. Which of the following is an example of potential energy?
A) Energy of a moving train
B) Energy of a coiled spring
C) Energy of a sound wave
D) Energy of heat
25. A car of mass 1000 kg is moving at 20 m/s. If brakes are applied and it stops, the work done by the braking force is:
A) 200,000 J
B) -200,000 J
C) 100,000 J
D) -100,000 J
26. The work done by friction is always:
A) Positive
B) Negative
C) Zero
D) Can be positive or negative
27. A spring is compressed by 0.1 m. If the spring constant is 200 N/m, the potential energy stored is:
A) 1 J
B) 2 J
C) 10 J
D) 20 J
28. A block of mass 5 kg is lifted vertically by 3 meters. The work done against gravity is:
A) 15 J
B) 3 J
C) 5 J
D) 150 J
29. If an object's kinetic energy is 100 J and its mass is 2 kg, what is its velocity?
A) 5 m/s
B) 10 m/s
C) 20 m/s
D) 100 m/s
30. A 2 kg object moves with a velocity of 4 m/s. Its kinetic energy is:
A) 4 Joules
B) 8 Joules
C) 16 Joules
D) 32 Joules
31. In the absence of non-conservative forces, the total mechanical energy (Kinetic Energy + Potential Energy) of a system is:
A) Decreased
B) Increased
C) Conserved
D) Zero
32. When the ball in the previous question hits the ground, its potential energy is:
A) mgh
B) 1/2 mgh
C) 0
D) Maximum
33. A ball of mass 'm' is dropped from a height 'h'. Its potential energy at height 'h' is:
A) 0
B) mgh
C) 1/2 mgh
D) mg/h
34. What is the potential energy of an object at the ground level (reference point)?
A) Maximum
B) Minimum
C) Zero
D) Infinite
35. When is the work done by a force zero?
A) When the force is zero
B) When the displacement is zero
C) When the force and displacement are perpendicular
D) All of the above
36. If a force of 10 N acts on an object and displaces it by 5 meters in the direction of the force, the work done is:
A) 2 Joules
B) 50 Joules
C) 15 Joules
D) 0.5 Joules
37. The work done by a force F acting on an object that undergoes a displacement d is given by:
A) F/d
B) F * d
C) F + d
D) F - d
38. A body is moving with a constant velocity. The net work done on it is:
A) Positive
B) Negative
C) Zero
D) Indeterminate
39. If the net work done on an object is negative, its kinetic energy:
A) Increases
B) Decreases
C) Remains constant
D) Becomes infinite
40. If the net work done on an object is positive, its kinetic energy:
A) Decreases
B) Increases
C) Remains constant
D) Becomes zero
41. The work-energy theorem states that the net work done on an object is equal to the change in its:
A) Potential energy
B) Kinetic energy
C) Total mechanical energy
D) Linear momentum
42. A spring has potential energy stored in it when it is:
A) At its natural length
B) Compressed or stretched
C) Moving with constant velocity
D) At rest
43. Gravitational potential energy near the Earth's surface is given by:
A) 1/2 mv^2
B) mgh
C) MgR
D) Gm1m2/r^2
44. Potential energy is the energy possessed by an object due to its:
A) Motion
B) Velocity
C) Position or configuration
D) Mass
45. If the velocity of an object is doubled, its kinetic energy will be:
A) Halved
B) Doubled
C) Quadrupled
D) Tripled
46. The formula for kinetic energy (KE) is:
A) mgh
B) 1/2 mv^2
C) mv
D) m/v
47. Kinetic energy is defined as the energy possessed by an object due to its:
A) Position
B) Motion
C) State of matter
D) Temperature
48. The work done by a conservative force is:
A) Dependent on the path taken
B) Independent of the path taken
C) Always zero
D) Always negative
49. Which of the following is a scalar quantity?
A) Force
B) Velocity
C) Work
D) Momentum
50. What is the SI unit of work?
A) Joule
B) Watt
C) Newton
D) Pascal