Question

In which of the following cases is the work done non-zero?

• A. Rahul is standing still with a 30 kg weight on his head for 5 hours.
• B. Rohan is working hard to push a huge rock but the rock does not move despite all the effort.
• C. Rohan climbs the staircase to go to the second floor.
• D. All of these.

Answer 1

The correct option is C

Rohan climbs the staircase to go to the second floor.

Since there is no displacement in the first case, the product of force and displacement reduces to zero. So work done is zero. In the second case also there is no displacement. So work done is zero. In third case displacement is non-zero and force is also non-zero. So work done is non-zero.