Question

Is it possible that a force is acting on a body but still the work done is zero? Explain giving one example. Or What is the work done by a coolie walking on a level road with a load on his head?

Answer 1

Explanation

1. Yes, it is possible that a force is acting on a body but still the work done is zero.
2. For example, If we apply a force on a heavy stone and it does not move then the work done in that case would be zero.

Another example:

Consider a coolie carrying a load on his head across a level road.

1. He exerts an upward force equal to the weight of the load.
2. But the displacement of the load is in the horizontal direction.
3. Thus the angle between force $\text{'}F\text{'}$ and displacement $\text{'}s\text{'}$is $90°$.
4. As we know,

$W=FsCos\theta$

Then,

$$\begin{gathered} W=FsCos90° \\ \therefore Cos90°=0 \\ W=0 \end{gathered}$$

Hence, work done in this case would be zero.