Which of the following statement shows that no work is done?
Correct answer: E. C and D
- A. Pushing a car to start it moving
- B. Lifting the weights
- C. The moon orbiting the Earth
- D. Writing an essay on a page
- E. C and D
Explanation
When you lift weights, you apply a force (the gravitational force) to move the weights against gravity. Work is done because there is a force applied (lifting) and a displacement (the weights move vertically) in the direction of the force.
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About Work and Energy
Work transfers energy when a force causes displacement, while kinetic energy, gravitational potential energy and power describe motion, position and the rate of energy transfer. The work-energy theorem links net work with change in kinetic energy, and efficiency accounts for energy losses rather than treating them as energy destruction.
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