Answer to the Question 07/97
The question was:By how much can an upward jump of an acrobat be increased using a trampoline once.
(9/98) This problem has been solved correctly by Martin Doerr (e-mail doerr@ulb.ac.be) from Universite Libre de Bruxelles.
The answer: the height of the jump will be doubled.
The solution as was sent in by Doerr:
The acrobat jumps twice (once onto the trampoline and the second time from the trampoline). Since the trampoline does not give or take energy by itself (well, its an ideal trampoline, of course), the max kinetic energy he can have at the end is twice the one without trampoline. It is actually a little less, particularly if the trampoline is too hard, since his legs can't take the total acceleration (like for a steel trampoline, which works well with steel balls). If the tramp is too soft, he will also not be able to gain more than his initial (single jump) kinetic energy (try it). The period of the tramp must be matched to the artists optimal jump time (wouldn't you have guessed).
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