You are jumping on a trampoline and it occurs to you that energy is being transferred as you bounce. like your usual thoughts, doesn't it? ) you realize that sometimes you do work on the trampoline and sometimes it does work on you. the time when you do work on the trampoline is(a) whenever you are touching its surface. (b) when you are touching its surface and that surface is moving downward. (c) when you are touching its surface and that surface is moving upward. (d) during the second half of the trampoline's movement downward and the first half of the trampoline's movement upward.