Work, Power and Energy Quiz - ICSE Class 11 Physics

Free practice quiz: Work, Power and Energy (ICSE Class 11 Physics). 38 multiple-choice questions with answers and explanations. Play online, no sign-up needed.

This ICSE Class 11 Physics practice quiz has 38 multiple-choice questions on Work, Power and Energy, and 38 of them come with an explanation. Try the 5 sample questions below (tap an option to check yourself), then play the full quiz online. No sign-up needed.

Sample questions

1. A particle of mass m is projected vertically upwards with an initial velocity v. What is the work done by gravity when the particle reaches its maximum height?

   1. 0
   2. mv²/2
   3. -mv²/2
   4. mg(v²/2g)
   Show answer

   Answer: C. -mv²/2

   The initial kinetic energy is KE_i = mv²/2. At the maximum height, the velocity is zero, so the final kinetic energy is KE_f = 0. By the work-energy theorem, the work done by gravity (W_g) is equal to the change in kinetic energy: W_g = KE_f - KE_i = 0 - mv²/2 = -mv²/2. Alternatively, the maximum height reached is h = v²/2g. The work done by gravity is W_g = -mgh = -mg(v²/2g) = -mv²/2.

2. A 5 kg object is lifted vertically upwards by a force of 100 N. If the object starts from rest and reaches a height of 10 m, what is the work done by the applied force?

   1. 500 J
   2. 1000 J
   3. 490 J
   4. 50 J
   Show answer

   Answer: B. 1000 J

   The work done by a constant force is given by W = Fd, where F is the magnitude of the force and d is the displacement in the direction of the force. Here, the applied force is F = 100 N and the vertical displacement is d = 10 m. Therefore, the work done by the applied force is W = 100 N * 10 m = 1000 J. Note that the weight of the object is mg = 5 kg * 9.8 m/s² = 49 N. The net force is 100 N - 49 N = 51 N. The work done against gravity is 490 J. The work done by the applied force is 1000 J.

3. A 2 kg mass is moving with a velocity of 3 m/s. What is its kinetic energy?

   1. 3 J
   2. 6 J
   3. 9 J
   4. 18 J
   Show answer

   Answer: C. 9 J

   Kinetic energy (KE) is given by the formula KE = ½mv², where m is the mass and v is the velocity. Here, m = 2 kg and v = 3 m/s. So, KE = ½ * 2 kg * (3 m/s)² = 1 kg * 9 m²/s² = 9 J.

4. A block of mass 4 kg is pulled by a force of 16 N on a smooth horizontal surface. If it moves a distance of 5 m, what is the work done by the force?

   1. 16 J
   2. 64 J
   3. 80 J
   4. 320 J
   Show answer

   Answer: C. 80 J

   Work done by a constant force is given by W = F * d. Here, F = 16 N and d = 5 m. Since the force is applied horizontally and the displacement is horizontal, the angle between them is 0°, and cos(0°) = 1. Therefore, W = 16 N * 5 m = 80 J. The mass of the block is not required for this calculation.

5. A spring is compressed by 0.2 m from its equilibrium position. If the work done to compress it is 8 J, what is the spring constant?

   1. 100 N/m
   2. 200 N/m
   3. 400 N/m
   4. 800 N/m
   Show answer

   Answer: C. 400 N/m

   The work done in compressing a spring from its equilibrium position is given by W = ½kx², where k is the spring constant and x is the compression. We are given W = 8 J and x = 0.2 m. So, 8 J = ½ * k * (0.2 m)². 8 = ½ * k * 0.04. 8 = k * 0.02. k = 8 / 0.02 = 400 N/m.

More questions in this quiz

Answers and explanations are in the full quiz.

1. A spring of spring constant k is stretched by a distance x from its equilibrium position. What is the work done by the spring force during this stretching?
2. A 10 kg block is moved horizontally across a surface by a constant force of 50 N. If the displacement is 5 meters and the force makes an angle of 30° with the horizontal, what is the work done by the force?
3. A power of 100 W is used to lift a body of mass 50 kg to a certain height in 10 seconds. What is the work done?
4. A conservative force does work W on a particle as it moves from point A to point B. If the particle moves from point B to point A under the action of the same conservative force, what is the work done?
5. A body's kinetic energy increases from 10 J to 50 J. What is the work done by the net force on the body?
6. A particle of mass m is moving with a constant velocity v. What is its kinetic energy?
7. A system has potential energy U(x) = ax² + bx. If a force F(x) acts on the particle, which expression represents the force?
8. A car of mass 1000 kg is moving at 20 m/s. If its kinetic energy is doubled, by what factor does its speed increase?
9. A person holds a bag of mass m at a height h for time t. What is the work done by the person in holding the bag stationary?
10. A force F = (2x + 3) N acts on a particle along the x-axis. What is the work done by this force as the particle moves from x = 0 m to x = 2 m?
11. What is the SI unit of power?
12. A person pushes a box of mass 20 kg with a force of 50 N for 10 seconds. If the box moves with a constant velocity of 0.5 m/s, what is the work done by the person?
13. A spring is compressed by 0.1 m from its equilibrium position. If the spring constant is 400 N/m, what is the potential energy stored in the spring?
14. A force of 10 N acts on a particle of mass 5 kg. If the particle moves a distance of 2 m in the direction of the force, what is the work done by the force?
15. Which of the following is a non-conservative force?
16. A body of mass m is moving with velocity v. If its velocity is doubled, its kinetic energy will be multiplied by:
17. A pendulum bob of mass m swings through an angle θ from the vertical. What is the work done by gravity when the bob moves from its highest point to its lowest point?
18. A power of 500 W is supplied to a machine. How much work is done by the machine in 10 seconds?
19. A spring with spring constant k is stretched by x from its equilibrium position. The work done by the external agent to stretch the spring is:
20. A body's potential energy is given by U(x) = 5x² - 2x + 3. What is the force acting on the body?
21. A uniform rope of length L and mass M lies on a smooth horizontal table. One end of the rope is pulled vertically upwards with a constant speed v. What is the power delivered by the pulling force at the instant when a length y of the rope is off the table?
22. A particle of mass m is subjected to a force F that varies with position as shown in the graph. What is the work done by the force as the particle moves from x = 0 to x = 6?
23. A ball of mass 0.5 kg is thrown upwards with an initial velocity of 20 m/s. What is the maximum height reached by the ball, neglecting air resistance? (g = 10 m/s²)
24. The work done by a conservative force is equal to the negative of the change in:
25. A force F = 5 N is applied to a block of mass 2 kg, causing it to accelerate from rest. If the block moves a distance of 10 m, what is the work done by the force?
26. A car of mass 1000 kg travels at a constant speed of 20 m/s. If the engine provides a driving force of 500 N, what is the power output of the engine?
27. A particle moves from point A to point B under the action of a force. The work done by the force is independent of the path taken. This means the force is:
28. A block of mass 5 kg is at rest on a horizontal frictionless surface. A horizontal force of 10 N is applied for 4 seconds. What is the final kinetic energy of the block?
29. Which of the following quantities represents energy?
30. A spring is stretched by 0.1 m, and the work done is 5 J. What is the spring constant?
31. A constant force F is applied to a particle of mass m. If the particle moves from rest to a velocity v, the work done by the force is:
32. A spring is stretched such that its potential energy is U. If it is stretched further by the same amount, the additional work done will be:
33. A 5 kg block is pulled horizontally with a force of 20 N. If the block moves with a constant velocity, what is the work done by friction over a distance of 10 m?

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