Four men lift a 250 kg box to a height of 1 m and hold it without raising or lowering it. (i) How much work is done by men in lifting the box? (ii) How much work is done in just holding it? (Take `g=10ms^(-2)`).

Answer

(1) 2500 J (2) 0

Explanation

(3) To hold the box, they have to do work, against the gravitational force, using their muscular energy. Hence, they get fatigued.