A 10 ft chain weighs 55 lb and hangs from a ceiling. Find the work done (in ft-lb) in lifting the lower end of the chain to the ceiling so that it's level with the upper end.

Question

A 10 ft chain weighs 55 lb and hangs from a ceiling. Find the work done (in ft-lb) in lifting the lower end of the chain to the ceiling so that it's level with the upper end.

Answer 1

Work W = ∫₀^lP/l(l - y)dy = - P/l(l - y)²/2₀^l = Pl²/(2l) = Pl/2 = 55lb·10ft/2 = 275 ft-lb