Work done by constant and variable forces, kinetic and potential energies - Question Bank

1. If a force F = 2x^2 + 3x N acts on a particle, what is the work done in moving it from x=1m to x=2m?
A) 10 J
B) 7 J
C) 17 J
D) 10.5 J
2. What is the change in potential energy when an object of mass m is raised by a height h?
A) mgh
B) -mgh
C) Zero
D) mg/h
3. The work done by a force F = 3i + 2j N on a particle moving with velocity v = 2i + 3j m/s is:
A) 12 J
B) 6 J
C) 0 J
D) 18 J
4. If the net force acting on an object is zero, then the work done by the net force is:
A) Always positive
B) Always negative
C) Zero
D) Cannot be determined
5. The rate at which work is done is called:
A) Energy
B) Power
C) Momentum
D) Force
6. A force F = 5i N displaces a particle by d = 2j m. The work done is:
A) 10 J
B) 0 J
C) 7 J
D) 3 J
7. Which type of energy is associated with the configuration of a system?
A) Kinetic energy
B) Thermal energy
C) Potential energy
D) Chemical energy
8. In which of the following cases is the work done zero?
A) A man pushing a wall
B) A car moving on a road
C) A satellite orbiting the Earth
D) All of the above
9. Work done by a force is defined as the product of force and displacement only when the force is:
A) Variable
B) Zero
C) Constant and in the direction of displacement
D) Perpendicular to displacement
10. If the speed of a particle is constant, its kinetic energy:
A) Increases
B) Decreases
C) Remains constant
D) Becomes zero
11. A force F = kx^n acts on a particle, where k is a constant. The work done by this force when it moves from x = 0 to x = L is:
A) kL^(n+1)/(n+1)
B) kL^n
C) kL
D) kL^2/2
12. The unit of potential energy is the same as the unit of:
A) Force
B) Power
C) Work
D) Momentum
13. The work done by the gravitational force when a body moves from a higher altitude to a lower altitude is:
A) Positive
B) Negative
C) Zero
D) Infinite
14. If the net work done on an object is positive, its kinetic energy:
A) Decreases
B) Increases
C) Remains the same
D) Becomes zero
15. When a ball is thrown upwards, its potential energy:
A) Increases
B) Decreases
C) Remains constant
D) First increases then decreases
16. The kinetic energy of a body is 100 J. If its velocity is doubled, the new kinetic energy will be:
A) 200 J
B) 400 J
C) 100 J
D) 50 J
17. A force is given by F = (2t + 5) N. What is the work done by this force from t = 0 s to t = 2 s, assuming the force acts in the direction of motion?
A) 14 J
B) 7 J
C) 24 J
D) 12 J
18. What is the potential energy of a system when its constituent particles are infinitely far apart (for attractive forces)?
A) Maximum
B) Minimum
C) Zero
D) Infinite
19. A particle moves from point A to point B under the influence of a force. The work done by this force is independent of the path taken if the force is:
A) Frictional
B) Conservative
C) Variable
D) Non-conservative
20. The work done by the centripetal force in circular motion is:
A) Positive
B) Negative
C) Zero
D) Variable
21. If the momentum of a body is doubled, its kinetic energy becomes:
A) Double
B) Four times
C) Half
D) Remains the same
22. Which of the following is NOT a unit of energy?
A) Joule
B) Erg
C) Calorie
D) Newton-meter
23. When is the work done by a force negative?
A) When the angle between force and displacement is acute
B) When the angle between force and displacement is obtuse
C) When the angle between force and displacement is 90 degrees
D) When there is no displacement
24. A spring is compressed by 2 cm. If the spring constant is 100 N/m, what is the potential energy stored in the spring?
A) 0.02 J
B) 0.01 J
C) 0.04 J
D) 0.005 J
25. The potential energy of a system is minimum when the system is in a state of:
A) Unstable equilibrium
B) Neutral equilibrium
C) Stable equilibrium
D) Maximum energy
26. If an object is moving with constant velocity, the net work done on it is:
A) Positive
B) Negative
C) Zero
D) Cannot be determined
27. A force F(x) = 5x^2 N acts on a particle. The work done by this force as the particle moves from x = 1 m to x = 3 m is:
A) 10 J
B) 20 J
C) 40 J
D) 12 J
28. Potential energy is defined for:
A) All types of forces
B) Conservative forces only
C) Non-conservative forces only
D) Frictional forces only
29. What is the change in kinetic energy if an object's speed changes from v1 to v2?
A) 1/2 m(v1^2 - v2^2)
B) 1/2 m(v2^2 - v1^2)
C) m(v2 - v1)
D) 1/2 m(v1 + v2)^2
30. The work done by friction is always:
A) Positive
B) Negative
C) Zero
D) Can be positive or negative
31. A force F = 3i + 4j N acts on a particle and displaces it by d = (2i - 3j) m. The work done is:
A) 18 J
B) -6 J
C) 6 J
D) 0 J
32. Which of the following represents the potential energy of a particle in simple harmonic motion?
A) 1/2 mv^2
B) 1/2 kx^2
C) mgh
D) F*d
33. If an object is at rest, its kinetic energy is:
A) Maximum
B) Minimum
C) Zero
D) Infinite
34. The work done in lifting a body of mass 'm' to a height 'h' is:
A) mgh
B) mg/h
C) m/gh
D) gh/m
35. If the potential energy of a system is decreasing, the work done by the conservative force is:
A) Positive
B) Negative
C) Zero
D) Infinite
36. A variable force is given by F = (2x + 3) N, where x is in meters. What is the work done by this force when it moves an object from x = 0 m to x = 2 m?
A) 10 J
B) 4 J
C) 6 J
D) 8 J
37. When a body falls freely under gravity, its total mechanical energy:
A) Increases
B) Decreases
C) Remains constant
D) May increase or decrease
38. The work-energy theorem states that the net work done on an object is equal to the change in its:
A) Potential energy
B) Total energy
C) Kinetic energy
D) Momentum
39. For a spring, the potential energy is given by:
A) kx
B) 1/2 kx
C) 1/2 kx^2
D) kx^2
40. What is the formula for gravitational potential energy near the Earth's surface?
A) 1/2 mv^2
B) mgh
C) GMm/r
D) kT
41. Potential energy is the energy possessed by an object due to its:
A) Motion
B) Velocity
C) Position or configuration
D) Temperature
42. If the velocity of an object is doubled, its kinetic energy becomes:
A) Half
B) Double
C) Four times
D) Remains the same
43. If the mass of an object is doubled, its kinetic energy becomes:
A) Half
B) Double
C) Four times
D) Remains the same
44. What is the formula for kinetic energy?
A) mgh
B) 1/2 mv^2
C) F*d
D) PV
45. Kinetic energy is the energy possessed by an object due to its:
A) Position
B) Motion
C) State
D) Chemical composition
46. The work done by a non-conservative force is:
A) Path independent
B) Path dependent
C) Always zero
D) Always positive
47. The work done by a conservative force is:
A) Always positive
B) Always negative
C) Path independent
D) Path dependent
48. Which of the following is a scalar quantity?
A) Force
B) Velocity
C) Work
D) Acceleration
49. Work done by a force is zero if the displacement is:
A) In the direction of the force
B) Opposite to the direction of the force
C) Perpendicular to the direction of the force
D) Zero
50. If a force of 10 N acts on an object and displaces it by 5 meters in the direction of the force, what is the work done?
A) 50 J
B) 5 J
C) 15 J
D) 2 N-m
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