100+ Work Energy And Power (Class 11) MCQs PDF

Work Energy And Power (Class 11) MCQs PDF are must for the aspirants who are preparing for various competitive examination. It covers the concept of Work, Energy and Power which is very important for any competitive exams. This Law of Work, Energy and Power topic is given most importance in various competitive exams like JEE Main, JEE Advanced, NEET, AIIMS etc.

Work Energy And Power (Class 11) MCQs PDF

These Work Energy And Power (Class 11) MCQs are based on the following topics:

Introduction to Work, Energy and Power MCQs and Answers
Work-Energy Theorem MCQs and Answers
Work MCQs and Answers
Kinetic Energy MCQs and Answers
Work Done by a Variable Force MCQs and Answers
Friction MCQs and Answers
Work-Energy Theorem for a Variable Force MCQs and Answers
Potential Energy MCQs and Answers
The Potential Energy of a Spring MCQs and Answers
The Law of Conservation of Energy MCQs and Answers
Power MCQs and Answers
Collision MCQs and Answers

Work Energy And Power (Class 11) MCQs PDF

1. A body having 7 kg of mass moves with a velocity of 20 m/s covers a vertical height of 8.75 m. What is the work done by the moving force in Joules? Take g = 10 m/s2.

a) 0

b) 10

c) 15

d) 20

Answer: a

2. A projectile has both change in kinetic and potential energy. Still the work done calculated between any two points is zero. This is due to _________

a) Presence of no external force

b) No displacement

c) The displacement being in both vertical and horizontal directions

d) Inter-conversion of kinetic and potential energies

Answer: d

3. A body having 7 kg of mass moves slowly and covers a vertical height of 14 m. What is the work done in Joules and what force causes this work? Take g = 10 m/s2.

a) 980, gravity

b) 980, force acting opposite to gravity

c) 1000, gravity

d) 1000, force acting opposite to gravity

Answer: a

4. The total energy of a system moving under the action of a conservative force changes by 50 J. Which of the following statements are correct with regards to the amount of work done?

a) Amount of work done = 50 J

b) Amount of work done < 50 J

c) Amount of work done > 50 J

d) Amount of work done <= 50 J

Answer: a

5. A body of mass 2 Kg, initially at rest, moves under the influence of an external force of magnitude 4 N on plane ground. What is the work done by the force and the change in kinetic energy in the first 10 seconds?

a) 400 J, 400 J

b) -400 J, 400 J

c) 400 J, -400 J

d) -400 J, -400 J

Answer: a

6. A body moving with a constant velocity on normal ground initially has an energy of 1000 J. If the final energy is 800 J, what is the work done and which force causes this work?

a) 200 J, gravity

b) -200 J, friction

c) 200 J, friction

d) -200 J, gravity

Answer: b

7. According to the work-energy theorem, total change in energy is equal to the _______

a) Total work done

b) Half of the total work done

c) Total work done added with frictional losses

d) Square of the total work done

Answer: a

8. The work done by a body while covering a vertical height of 5m is 50 kJ. By how much amount has the energy of the body changed?

a) 50 kJ

b) -50 kJ

c) 25 kJ

d) 10 kJ

Answer: a

9. Power is ______

a) Rate of doing work

b) Ability to do work

c) Rate of energy creation

d) Equivalent to work

Answer: a

10. The unit of energy has been named after ______

a) James Prescott Joule

b) John Prescott Joule

c) Jammie Joule

d) Jessy Joule

Answer: a

11. In which category do potential and kinetic energy fall?

a) Mechanical energy

b) Electrical energy

c) magnetic energy

d) Usual energy

Answer: a

12. How many Ergs are there in 1 Joule?

a) 10

b) 104

c) 107

d) 109

Answer: c

13. What is the correct expression for power?

a) P = dW/dt

b) P = F * d

c) P = E

d) P = dE/dt

Answer: a

14. What is the correct expression for Work?

a) W = F * ds

b) W = P/t

c) W = E

d) W = E/t

Answer: a

15. Energy involved in creating work _____

a) Gets used up

b) Gets transferred

c) Gets exhausted

d) Gets lost

Answer: b

16. The energy possessed by a body by the virtue of its motion is called ______

a) Kinetic energy

b) Potential energy

c) Total energy

d) Motion energy

Answer: a

17. The energy possessed by a body by the virtue of its position is called ______

a) Kinetic energy

b) Potential energy

c) Total energy

d) Position energy

Answer: b

18. Energy is ________

a) Work

b) The ability to create work

c) Quantification of work

d) Force multiplied by displacement

Answer: b

19. The change in the total energy of a body moving because of work being done on it is attributed by the change in kinetic energy only when ______

a) It moves extremely slowly

b) It moves with a very high velocity

c) It moves on an equipotential surface

d) It moves with a positive acceleration

Answer: c

20. The total energy change of a body which covers a vertical height is constituted completely by the potential energy change only when ______

a) It moves slowly

b) It moves quickly

c) It moves for some time, then rests, then moves again

d) It moves with a decreasing velocity

Answer: a

21. Work being a scalar quantity sometimes has negative and positive signs. What does the sign suggest?

a) The direction of work

b) Relative directions of force and displacement

c) The direction of force

d) The direction of displacement

Answer: b

22. A force of 40 N acts on body of mass 5 Kg which is initially at rest. What is the amount of work done in the first 10 s?

a) 16000 J

b) -16000 J

c) 400 J

d) -400 J

Answer: a

23. The work done on a body of mass 5 Kg is 70 J. What is the magnitude of the force applied if the total displacement it covered is 7 m.

a) 10 N

b) -10 N

c) 20 N

d) 70 N

Answer: a

24. A body of mass 40 Kg covers a distance of 50 m in 5s starting from rest under the influence of a force. What is the work done by the force on the body?

a) 8000 J

b) -8000 J

c) 20000 J

d) 800 J

Answer: a

25. A block of mass 10 Kg accelerates from rest to a velocity of 20 m/s in 5s under the influence of an external force. What is the work done by the external force?

a) 2000 J

b) -2000 J

c) 20000 J

d) -20000 J

Answer: a

26. A force of 10 N creates a displacement of 2 m but the work done on the body throughout its motion is equal to 70 J. What possibly can be the reason or this?

a) There are multiple forces action on the body

b) The body is at rest

c) The force is not uniform

d) The displacement is harmonic

Answer: a

27. Work done by a force on a body is an example of ______

a) Mechanical work

b) Electrical work

c) Magnetic work

d) Thermodynamic work

Answer: a

28. Work done in a system is ___

a) The measure of energy change

b) The measure of useful work

c) The measure of displacement

d) The measure of force

Answer: a

29. Work is a _______

a) Scalar quantity

b) Vector quantity

c) Foreign quantity

d) Magnitude less quantity

Answer: a

30. A force of 40 N acts on body of mass 5 Kg. What is the amount of work done if the total displacement is 2 m and is in the direction of the force applied?

a) 80 J

b) -80 J

c) 40 J

d) 16 J

Answer: a

31. The kinetic energy of a body is ‘K’. If one-fourth of its mass is removed and velocity is doubled, the new kinetic energy will be _____

a) K

b) 3K

c) 4K

d) 9K/4

Answer: b

32. Which of the following is correct?

a) The kinetic energy of a system can be changed without changing the momentum

b) The kinetic energy of a system cannot be changed without changing the momentum

c) The momentum of a system cannot be changed without changing its kinetic energy

d) A system cannot have energy without having momentum

Answer: a

33. A person whose mass is 90kg is standing on a smooth horizontal platform. He throws a rock of mass 10kg horizontally on the same surface. If the distance between the person and the rock after 10 seconds is 10 m, what is the kinetic energy of the person?

a) 0.45 J

b) 4.5 J

c) 0.9 J

d) 0 J

Answer: b

34. The kinetic energy of a man is half that of a boy whose mass is half that of the man. When the man speeds up by 5 m/s, his kinetic energy doubles that of the boy’s kinetic energy. What is the initial velocity of the man?

a) 5 m/s

b) 10 m/s

c) 15 m/s

d) 20 m/s

Answer: a

35. What kinetic energy should be imparted to an object of mass “m” to raise it to a height of 1000 meters? (Take g = 10 m/s2)

a) 10m J

b) 100m J

c) 1000m J

d) 10000m J

Answer: d

36. For an object of 1kg mass to escape the gravitational force of the earth, the kinetic energy imparted to it from the surface of the earth is approximately _____

a) 5600 J

b) 10200 J

c) 11200 J

d) 12000 J

Answer: a

37. A body is projected up vertically with a velocity of 60 m/s. What percentage of its initial kinetic energy is converted into potential energy after 3 seconds? (Take g = 10 m/s2)

a) 25 %

b) 50%

c) 75%

d) 100%

Answer: c

38. A body is falling freely from rest from a height of 100m. The ratio of kinetic energy after 2 and 5 seconds is _____

a) 2:5

b) 4:25

c) 25:4

d) 5:2

Answer: b

39. A particle of mass 1kg is moving with a velocity of 20ms-1 then its kinetic energy is ____

a) 200 J

b) 200 kgm2s-1

c) 200 kgm-1s-2

d) 200 kgm-1s-1

Answer: a

40. A particle of mass 200g is thrown vertically upwards with a speed of 10ms-1, the work done by force of gravity while the particle goes up is given by _____

a) 0.5J

b) 5J

c) 10J

d) 15J

Answer: c

41. A bucket filled with water weighing 20 kg is raised from a well of depth 20 m. If the linear density of the rope is 0.2 kg/m, the work done is _____ (Assume g = 10m/s2)

a) 4000 J

b) 4040 J

c) 4400 J

d) 4800 J

Answer: c

42. A force F = (5i – 3j +2k) N moves a particle from r1 = (2i + 7j + 4k) m to r2 = (5i + 2j + 8k) m. What is the work done by the force?

a) 18 J

b) 28 J

c) 38 J

d) 48 J

Answer: c

43. A person of mass 50 kg carrying a load of 20 kg walks up a staircase. The width and height of each step are 0.25 m and 0.2 m respectively. What is the work done by the man in walking 20 steps?(Assume g = 10m/s2)

a) 800 J

b) 1600 J

c) 2000 J

d) 2800 J

Answer: d

44. A chain of length 4 m is kept on a table. 2 m of the chain hangs freely from the table’s edge. The mass of the whole chain is 8 kg. What is the work done to pull the whole chain onto the table? (Assume g = 10m/s2)

a) 20 J

b) 40 J

c) 60 J

d) 80 J

Answer: b

45. The area under the force (F) versus displacement (x) graph gives work.

a) True

b) False

Answer: a

46. An object of mass 1kg is subjected to a variable force in x-direction. The force function is F = x2 N. What is the work done in moving the object from x = 2 to 5?

a) 40

b) 39

c) 38

d) 69

Answer: b

47. What is the SI unit of variable force?

a) Newtons

b) Joules

c) Ampere

d) Mole

Answer: a

48. A spring is stretched by a length x, then the potential energy stored in it changes by 0.5*k*x2, where k is the spring constant.

a) True

b) False

Answer: a

49. A force of 600 N elongates a spring from its natural length of 18 cm to a length of 20 cm. What is the work done?

a) 116J

b) 114J

c) 118J

d) 120J

Answer: b

50. Which of the following is not a variable force?

a) F = x

b) F = y2

c) F = 2

d) F = 2*t

Answer: c

51. Which of the following is not a conservative force?

a) Gravitational force

b) Spring force

c) Friction force

d) Magnetic force

Answer: c

52. A force F = x + 1 N acts on a particle in x direction. What is the work done from x = 2m to 5 m?

a) 10.5 J

b) 14.5 J

c) 13.5 J

d) 0.5 J

Answer: c

53. What is the value of spring constant if force of 200 N is acting on it and the spring is compressed by 2m?

a) 100 kgs-2

b) 100 kgs-1

c) 100 kg2s2

d) 100 Kgs

Answer: a

54. The length of a smooth inclined plane of 30-degree inclination is 5 m. The work done in moving a 10 kg mass from the bottom of the inclined plane to the top is _____ Joules. (Assume g = 10m/s2)

a) 250

b) 1000

c) 1250

d) 500

Answer: a

55. A rope has a uniform mass density of 0.4 kg/m. The rope is 10 m long and is lowered into a 10 m deep pit. The bottom part of the rope just touches the bottom of the pit. What is the work done to pull the rope out of the well completely? (Assume g = 10m/s2)

a) 200 J

b) 400 J

c) 2000 J

d) 4000 J

Answer: a

56. The value of the frictional force for a body is always constant when it is static and does not vary with applied force.

a) True

b) False

Answer: b

67. Consider a block of mass 9.81kg on an inclined surface of the coefficient of friction 0.15 and angle of inclination 30 degrees. What will be its acceleration on the inclined plane if acceleration due to gravity is 9.81 m/s2?

a) 3.63 m/s2

b) 4.63 m/s2

c) 9.81 m/s2

d) 10 m/s2

Answer: d

58. A “variable force” is the force that only increases with time.

a) True

b) False

View Answer

Answer: b

59. For a body moving from position Xa to position Xb under a variable force, what is the work done?

a) W = F * (X2 – X1)

b) -W = F * (X2 – X1)

c) W = -F * (X2 – X1)

d) W = F * (X1 – X2)

Answer: a

60. A car having a mass of 1 metric ton is moving with a speed of 30 m/s. It suddenly applies the brakes and skids to rest in a certain distance d. The frictional force between the tyres and road is 6000 N. What is the value of d?

a) 25 m

b) 50 m

c) 75 m

d) 100 m

Answer: c

61. An object is thrown from the ground with a velocity of 5 m/s. If the object has a mass of 2kg, what will be its potential energy at the top-most point of its trajectory? (Assume g = 10 m/s2)

a) 5 J

b) 15 J

c) 25 J

d) 50 J

Answer: c

62. Which of the following is true?

a) Potential energy decreases as altitude increases

b) Potential energy increases as altitude increases

c) Potential energy first increases and then decreases as altitude increases

d) Potential energy first decreases and then increases as altitude increases

Answer: b

63. Since the potential energy of an object depends on the acceleration due to gravity and since the acceleration due to gravity decreases as altitude increases, we can conclude that the potential energy of an object decreases as altitude increases.

a) True

b) False

Answer: b

64. Consider 2 balls A and B of the same mass. The potential energy of ball A is thrice that of ball B. How high is ball A compared to ball B?

a) Same height as ball B

b) Twice as high height as ball B

c) Thrice as high height as ball B

d) Four times as high height as ball B

Answer: c

65. The potential energy of an object of constant mass and fixed reference is determined by its _____

a) mass

b) gravitational acceleration

c) position

d) velocity

Answer: c

66. The potential energy of an object cannot be increased by internal forces.

a) True

b) False

Answer: a

67. Find the ratio of potential energy if an object is raised to thrice of its height and its mass is tripled.

a) 1:1

b) 1:4

c) 1:9

d) 1:3

Answer: c

68. The potential energy of an object maximises as its velocity increases.

a) True

b) False

Answer: b

69. An object of mass 5kg is taken from a height of 10 m to a height of 30 m. What is the increment in its potential energy? (Assume g = 10m/s2)

a) 500 J

b) 1000 J

c) 1500 J

d) 2000 J

Answer: b

70. A 10kg object is raised to a height of 20m. What is the magnitude of its potential energy? (Assume g = 10 m/s2)

a) 500 J

b) 1000 J

c) 1500 J

d) 2000 J

Answer: d

71. How much should a spring of indefinite length be compressed to have a potential energy equivalent to a ball of mass 6 kg raised to a height of 120 m above the ground? Let the spring have a stiffness of k = 100 N/m and assume g = 10 m/s2.

a) 6m

b) 12m

c) 20m

d) 144m

Answer: b

72. Assume a spring extend by “d” due to some load. Let “F” be the spring force and “k’ the spring constant. Then, the potential energy stored is _____

a) 2d/F2

b) F2/2k

c) 2k/T2

d) F2/2d

Answer: b

73. A spring of length 1m has two cars connected to both of its ends. The two cars move towards each other such that the spring is compressed to 0.5m. If the spring constant is 500 N/m, what is the elastic potential energy stored?

a) 125 J

b) -125 J

c) 62.5 J

d) -62.5 J

Answer: c

74. What is the increase in potential energy storage when the compression distance is doubled in a spring obeying Hooke’s law?

a) No increase

b) 100% increase

c) Cannot be determined

d) 4 times

Answer: d

75. The elastic potential energy varies linearly with displacement.

a) True

b) False

Answer: b

76. The potential energy possessed by a spring is also known as _____

a) Elastic potential energy

b) Extensive potential energy

c) Compressive potential energy

d) Deflection potential energy

Answer: a

77. The law of conservation of energy is not applicable to mechanical systems as they require energy input to keep working.

a) True

b) False

Answer: b

78. The energy possessed by an object because of its motion is termed _____

a) potential energy

b) kinetic energy

c) nuclear energy

d) solar energy

Answer: b

79. The maximum potential energy in a roller coaster is at _____

a) the top of the steep climb

b) somewhere during the climb

c) somewhere during the descent

d) the lowest point after the climb

Answer: a

80. Fire is a form of _____

a) solar energy

b) thermal energy

c) gravitational energy

d) kinetic energy

Answer: b

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