Question

A person holds a bundle of hay over his head for $30minutes$ and gets tired. Has he done some work or not? Justify your solution.

Answer 1

Explanation:

Work is done when the following two conditions are satisfied:

1. A force should act on a body.
2. There should be a displacement of the body due to the application of the force either in the direction of the force or in the opposite direction of the force.

From the above conditions, we can conclude that:

1. When the person holds the bundle over his head, the displacement of the body is zero.
2. The force applied by the person on the bundle is also zero, although the weight of the bundle is acting on the bundle.
3. Here the person gets tired because of muscular fatigue. In the muscles, the chemical energy converts into thermal energy due to muscular effort, the muscles get strained, and this causes muscular fatigue.
4. Therefore the work done by the person is zero.

Hence, the person did not do any work.