Work, Energy and Power Quiz - CBSE Class 11 Science
Free practice quiz: Work, Energy and Power (CBSE Class 11 Science). 18 multiple-choice questions with answers and explanations. Play online, no sign-up needed.
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A force of 10 N acts on an object causing it to move 5 meters in the direction of the force. What is the work done?
- 0 J
- 50 J
- 5 J
- 100 J
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Answer: B. 50 J
Work done = Force × Distance × cos(θ), where θ is the angle between the force and displacement. Since the force and displacement are in the same direction, θ = 0°, and cos(0°) = 1. Therefore, Work done = 10 N × 5 m = 50 J.
What is power?
- The rate of doing work
- The amount of work done
- The force applied
- The distance moved
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Answer: A. The rate of doing work
Power is the rate at which work is done or energy is transferred.
State the work-energy theorem.
- Work done = change in potential energy
- Work done = change in kinetic energy
- Work done = potential energy + kinetic energy
- Work done = force x displacement
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Answer: B. Work done = change in kinetic energy
The work-energy theorem states that the net work done on an object is equal to the change in its kinetic energy.
What is the efficiency of a machine that does 100 J of useful work when 200 J of energy is supplied to it?
- 50%
- 100%
- 200%
- 0%
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Answer: A. 50%
Efficiency = (Useful work output / Energy input) × 100% = (100 J / 200 J) × 100% = 50%
A pendulum swings back and forth. Describe the energy transformations that occur during one complete swing, neglecting air resistance.
- Potential energy is converted to kinetic energy and back again
- Kinetic energy is converted to potential energy and back again
- Both potential and kinetic energies remain constant
- Only kinetic energy is involved
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Answer: A. Potential energy is converted to kinetic energy and back again
At the highest point of its swing, the pendulum has maximum potential energy and minimum kinetic energy. As it swings down, potential energy converts to kinetic energy, reaching maximum kinetic energy at the bottom. As it swings back up, kinetic energy converts back to potential energy.