Four men lift a 300 kg box to a height of 1 m and hold it without raising or lowering it. (a) How much work is done by the men in lifting the box? (b) How much work do they do in just holding it? (c) Why do they get tired while holding it? (g = 10 m s –2 )

Question

Four men lift a 300 kg box to a height of 1 m and hold it without raising or lowering it. (a) How much work is done by the men in lifting the box? (b) How much work do they do in just holding it? (c) Why do they get tired while holding it? (g = 10 m s &#x2013;2 )

Philoid · Accepted Answer

(a) Force = mass x g = 300 x 10 = 3000N

Distance, s = 1m

W = F.s = 3000 J

(b) work done just holding it is zero; as the box does not move at all.

Such that W = F.s = F (0) = 0

(c) The force applied by the man in holding it is equal and opposite to the gravitational force applied on the box, while applying the force, muscular effort is involved. So they feel tired.

Four men lift a 300 kg box to a height of 1 m and hold it without raising or lowering it.(a) How much work is done by the men in lifting the box?(b) How much work do they do in just holding it?(c) Why do they get tired while holding it? (g = 10 m s–2)

Four men lift a 300 kg box to a height of 1 m and hold it without raising or lowering it.
(a) How much work is done by the men in lifting the box?

(b) How much work do they do in just holding it?

(c) Why do they get tired while holding it? (g = 10 m s^–2)