# physcis

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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

• physcis -

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

power input= 5kW

efficiency fraction= lifting power/5kw

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