Question

What is the amount of work done by:
(a) A weight - lifter in holding a weight of $120kg$ on his shoulder for $30s$.
(b) A locomotive against gravity, if it is travelling on a plane road.

Answer 1

Work done = Force x displacement

(a) There is no displacement of weight-lifter. Hence, no work done by weight-lifter.

(b) Work done by locomotive against gravity is zero, as it has no displacement along or opposite to the direction of gravity.