Question

If you just stand still on an escalator (moving stairway), it takes 20 seconds for it to carry you up one floor, about 5 meters. But if you walk up, you get to the top of the escalator in only 12 seconds.

(a) How much work does the escalator do in lifting you up to the next floor, it you just stand there?

(b) How much if you walk up the escalator?

(c) Some people expect the answer in part (b) to be the same as in part (a), saying that the escalator is still exerting the same force over the same distance; some people expect it to be more, saying that when your walk up your feet press down harder on the stairs than the do if you just stand, so the force is greater; and some people expect it should be less, saying that you're expending energy, so the escalator must expend less. Explain the problem with the reasoning by the folks who have it wrong.

Answer 1