Trevor lifts a 10kg box to the top of a cliff which is 20m high, in half an hour, then drops the box over the cliff. How much power did he use to lift the box?

Does the distance travelled by an oscillating mass between times t=0 and t2 equal the displacement of the particle over the same time period if t2> t/2? hint: consider a sine wave starting at t1=0, then consider a closing wave starting at t1=0, for your explanation.