Question

A boy of mass m climbs up a staircase of vertical height h. What is the work done by the boy against the force of gravity? What would have been the work done if he uses a lift in climbing the same vertical height?

Answer 1

When the boy of mass mm climbs through a vertical height hh, the work done against gravity is

W = mgh

If he uses a lift to reach the same vertical height hh, the work done against gravity is still

W = mgh

So, in both cases,

W = mgh​

because the work done against gravity depends only on the vertical height gained, not on the path taken.