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Question
A person holds a bundle of hay over his head for 30 minutes and gets tired. Has he done some work or not? Justify your answer.
Solution
Work is done whenever the given two conditions are satisfied:
- A force acts on the body.
- There is a body displacement by applying force in or opposite to the direction of force.
- A person holding a bundle of hay on his head becomes exhausted due to muscular weariness. This tiredness is caused by converting chemical energy into heat energy via muscular effort. The guy has done no work because his exertion does not cause the bundle over his head to move, i.e., s = 0.
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