Question

what is the work done by a coolie against the gravity​

Answer 1

Work done by a coolie against gravity can be easily calculated by the formula,

                                              $w = m*g*h$

But in the case of coolie, the work done by him is going to be zero. It can be visualized that, there will be some vertical displacement in lifting the luggage. But, when he will put the luggage back to the ground the vertical displacement will become zero.

Since the work depends on the height, the work done will become zero.