Question

When do we say that work is done? Write the formula for the work done by a body in moving up against gravity. Give the meaning of each symbol which occurs in it.

Answer 1

The necessary condition for a force to do work is: the applied force must cause a displacement along the direction of the force.
Work done can be negative, positive or zero depending upon the direction of motion and force applied.
We can calculate the work done against gravity in moving a body of mass (m) by a height  (h) as, Work done in lifting a body = (Weight of body) × (Vertical distance)
So, W = m × g × h
Where,
(W) - Work done
(m) - Mass of body
(g) - Acceleration due to gravity
(h) - Height through which the body is lifted