A crane whose motoer has a power input of 5.0kW lifts a 1200-kg load of bricks through a height 30m in 90s. Find the efficency of the crane which is the ratio between its output power and its input power

Answer 1

power in lifting= mgh/time=1200*9.8*30/90

power input= 5kW

efficiency fraction= lifting power/5kw