help with physics?

Question

a block and tackle is used to lift a load weighing 600 lb. the operator lifts the load a distance of 1.25 ft. by pulling on the rope with a force of 200 lb. over a distance of 4 ft.

a. input work= _____ft(lb)
b. output work=_____ft(lb)
c. efficiency of block & tackle= _____%

Answer 1

W = F * d

a) 4 * 200 = 800
b) 1.25 * 600 = 750
c) b/a = 0.9375

Answer 2

a) input work = 200 lb x 4 ft = 800 ft*lb
b) output work = 600 lb x 1.25 ft = 750 ft*lb
c) eff = out / input = 0.9375 or 93.375 %

friction accounts for the minor loss