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Summary:: Strap a weight-measuring bathroom scale to your feet and jump on a trampoline: weight measurements at different points of each jump? What is the longest part of the cycle you are in the free-float frame?
I am studying Spacetime Physics 2nd ed. by Taylor and Wheeler at the suggestion of one of you fine physicists (thanks!). I need help with
Problem 2-2 (pg. 45) [paraphrased]:
Strap a weight-measuring bathroom scale to your feet and jump on a trampoline: (i) weight measurements at different points of each jump? (ii) When does the weight-measurement read zero? (iii) What is the longest part of the cycle you are in the free-float frame?
Answers so far: (i) I am impressed to note my cousin (non-science grad) pointed out to me that such a weight-measuring scale would be completely uncalibrated rather quickly ;) I wish I had thought of that. On the way up whilst still in contact with trampoline (I cheated and thought of Newton of course, but college physics courses were taken like about two decades ago so help me a bit please) there is a net acceleration upward meaning the force of the trampoline pushing up is stronger than your weight under gravity so the scale will register more than your rest weight being pressed on top and bottom (assuming that the bathroom scale works on compression); zero after leaving contact with the trampoline and thus airborne; on the way down whilst in contact with the trampoline this is the same as on the way up (net acceleration is upward) only instead of becoming airborne you cycle to stationary for and instant because the initial velocity is downward; (ii) whilst airborne; (iii) I'm lost here because there is no physical container that defines the boundary of the frame, there was typically a house or a railcar in the text and I'm not certain what my test particles would behave like: since the potential free-float frame begins just after losing contact with the trampoline and ends just before making contact again with the trampoline, do the test particles travel along the same parabola as me? It totally makes sense if the test particles are inside me though (and my skin is the boundary of the frame) lol
I am studying Spacetime Physics 2nd ed. by Taylor and Wheeler at the suggestion of one of you fine physicists (thanks!). I need help with
Problem 2-2 (pg. 45) [paraphrased]:
Strap a weight-measuring bathroom scale to your feet and jump on a trampoline: (i) weight measurements at different points of each jump? (ii) When does the weight-measurement read zero? (iii) What is the longest part of the cycle you are in the free-float frame?
Answers so far: (i) I am impressed to note my cousin (non-science grad) pointed out to me that such a weight-measuring scale would be completely uncalibrated rather quickly ;) I wish I had thought of that. On the way up whilst still in contact with trampoline (I cheated and thought of Newton of course, but college physics courses were taken like about two decades ago so help me a bit please) there is a net acceleration upward meaning the force of the trampoline pushing up is stronger than your weight under gravity so the scale will register more than your rest weight being pressed on top and bottom (assuming that the bathroom scale works on compression); zero after leaving contact with the trampoline and thus airborne; on the way down whilst in contact with the trampoline this is the same as on the way up (net acceleration is upward) only instead of becoming airborne you cycle to stationary for and instant because the initial velocity is downward; (ii) whilst airborne; (iii) I'm lost here because there is no physical container that defines the boundary of the frame, there was typically a house or a railcar in the text and I'm not certain what my test particles would behave like: since the potential free-float frame begins just after losing contact with the trampoline and ends just before making contact again with the trampoline, do the test particles travel along the same parabola as me? It totally makes sense if the test particles are inside me though (and my skin is the boundary of the frame) lol
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