Work and Energy Quiz - CBSE Class 12 Physics
Free practice quiz: Work and Energy (CBSE Class 12 Physics). 20 multiple-choice questions with answers and explanations. Play online, no sign-up needed.
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What is the work done when a force of 10 N moves an object 5 m in the direction of the force?
- 15 J
- 50 J
- 5 J
- 10 J
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Answer: B. 50 J
Work done (W) is calculated using the formula W = F × d, where F is the force and d is the distance. Here, W = 10 N × 5 m = 50 J.
If an object is moved 10 meters by a variable force, resulting in 100 J of work, what is the average force applied?
- 10 N
- 20 N
- 15 N
- 5 N
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Answer: A. 10 N
The average force can be found using the formula W = F × d. Rearranging gives F = W/d. Here, F = 100 J / 10 m = 10 N.
In an isolated system, the total energy remains constant due to which principle?
- Conservation of momentum
- Conservation of energy
- Conservation of mass
- None of the above
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Answer: B. Conservation of energy
The law of conservation of energy states that in an isolated system, the total energy remains constant; energy cannot be created or destroyed, only transformed.
If a spring is compressed and then released, what happens to the elastic potential energy?
- It is lost
- It converts to kinetic energy
- It converts to frictional energy
- It mass increases
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Answer: B. It converts to kinetic energy
When a compressed spring is released, the elastic potential energy stored in the spring is converted to kinetic energy as the spring returns to its original shape.
When is the kinetic energy of an object zero?
- When the object is moving fast
- When the object is at rest
- When the object is thrown
- When the object is falling
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Answer: B. When the object is at rest
Kinetic energy is defined as the energy of a moving object. Thus, when an object is at rest (not moving), its kinetic energy is zero.