Question

An elevator uses 100 000J of electrical energy to raise a load of 800 N through a height of 40m in a time of 20s. What fraction of the energy input was NOT transferred to the load? A) 32% B) 68% C) 80%D) 97%

Answer 1

W: work

F: force required to lift load; F = 800 N

d: distance lifted: d = 40 m

W = Fd = 800*40

W = 32000 J

If 100000J were exerted on a load for which only 32000J was necessary, the other 100000-32000 = 68000J was not transferred to the load.

68000/100000 = 0.68 = 68%