
#1
Nov808, 11:06 AM

P: 23

1. The problem statement, all variables and given/known data
A 60 kg person jumps from a platform onto a trampoline 10 m below, stretching it 1.0 m from its initial position. Assumin that the trampoline behaves like a simple elastic spring, how much will it stretch if the same person jumps from a height of 20 m? 2. Relevant equations Law of Conservation of Energy Ek = 0.5mv^2 Eg = mgh Ee = 0.5kx^2 Fx = kx 3. The attempt at a solution Really didn't understand the question at all. I figured since the guy is jumping of the platform, velocity at that instance would be 0. If the guy landed on the trampoline, his velocity would be 0 (but i don't know about this). The equillibrium of spring is 0 when the guy jumps of platform so there is no elastic potential. I am guessing there is some gravitational potential as the platform is above the trampoline. But I am consistently getting the wrong answer. The answer is 1.4 m. How would you get that? Thanks, I appreciate the help. 



#2
Nov808, 11:11 AM

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Can you start by writing out an equation representing the principle of conservation of energy?




#3
Nov808, 11:13 AM

P: 23

Ek1 + Eg1 + Ee1 = Ek2 +Eg2 +Ee2
0.5mv1^2 + mgh1 + 0.5kx1^2 +FaD = 0.5mv2^2 + mgh2 + 0.5kx2^2 +FfD 



#4
Nov808, 11:18 AM

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Trampoline QuestionSo, what type of energy does the system posses before the person jumps and what type of energy does the system posses after the person has landed on the trampoline? 



#5
Nov808, 11:50 AM

P: 23

I think. 



#6
Nov808, 12:06 PM

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#7
Nov808, 12:21 PM

P: 23

mgh1 = 0.5kx2^2
but how do i find K? I tried Fg/x which is 588 N/m. I don't know if that is correct tho Caz using that K value, I get a final answer of 6.3 m which is not even close to the answer at the back. Maybe the answer at the back is wrong? 



#8
Nov808, 12:42 PM

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(1) Where the person jumps from 10m (2) Where the person jumps from 20m 



#9
Nov808, 12:45 PM

P: 23

You're a Genius. Wait thats three. But I want to know why I cant find the k value the way I did. I used Fg/x to find K. Can you tell me what I did wrong? 



#10
Nov808, 12:56 PM

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#11
Nov808, 01:03 PM

P: 23

AcceleratioN?? How does he accelerate? Do you mean that he decelerates as he lands on the trampoline and his V = 0?



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