Energy, Work and Power

Energy, Work and Power problem 41

A child stands on the balcony and drops a stone to fall freely. His friend stands under the balcony and catches the stone. In doing so, the stone acts on his arm with force and performs 8.8 J of work. The mass of the stone is 160 g, and the friend catches it at a height of 120 cm from the ground. Air resistance can be ignored. At what height does the child drop the stone?


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