Question

Question 13
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.

Answer 1

Work is done whenever the given two conditions are satisfied:
$\to$ A force acts on the body.
$\to$ There is a displacement of the body by the application of force in or opposite to the direction of the force.
When a person holds a bundle of hay over his head, then there is no displacement in the bundle of hay. Although force of gravity is acting on the bundle, the person is not applying any force on it. Hence, in the absence of force, work done by the person on the bundle is zero.