(adsbygoogle = window.adsbygoogle || []).push({}); 1. The problem statement, all variables and given/known data

A 35 kg child is jumping on a pogo stick. If the spring has a constant of 4945 N/m and it is compressed 25 cm, how high will the child bounce?

Answer: 0.45 m

Need help substituting the right variable.

2. Relevant equations

E_{Ti}= E_{Tf}

E_{gi}+ E_{ki}+ E_{ei}= E_{gf}+ E_{kf}+ E_{ef}

mgh_{i}+ 0.5mv_{i}^{2}+ 0.5ks_{i}^{2}= mgh_{f}+ 0.5mv_{f}^{2}+ 0.5ks_{f}^{2}

3. The attempt at a solution

The real problem I have is setting the defined variables; everything I can solve for. I used trial and error and got 0.45 but I NEED TO KNOW WHY I use the variables (magnitudes in the right place)!

m = 35 kg

k = 4954 N/m

g = 9.8 m/s²

s_{i}= 0 m

s_{f}= 0.37 m

h_{i}= 0 m

h_{f}= ?

v_{i}= 0 m/s²

v_{f}= 0 m/s²

I rearranged and solved and I got -0.45 m, some please tell me where what variables I have to substitute correctly! Thank you!

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# Homework Help: Pogo Stick Elastic Energy: Substituting Correct Variables

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