Question

What will be the work done when a man stands with a 5-kg load on his head for 20 min? Explain.

Answer 1

The work done by the man is zero (0 Joules).

According to the laws of physics, mechanical work is said to be done only when an applied force produces a displacement in the body in the direction of that force.

W = Force × Displacement

In this scenario, although the man applies muscular force to hold the heavy 5-kg load on his head, he remains standing completely still at a single position for 20 minutes. Since there is no movement or change in the position of the load, its displacement is completely zero.

When displacement is zero, the product of force and displacement also becomes zero.

Therefore, despite the muscular strain and fatigue experienced by the man, no physical or mechanical work is performed against gravity.