Force, F = 250 × 10 = 2500 N
Displacement, s = 1 m
Work done = F × s = 2500 × 1 = 2500 J
(b) As there is no displacement in just holding the box, so no work is done i.e. Work done is zero.
(c) To hold the box men are applying force against the gravity, which involves their muscles to work, hence they get tired holding it.