# Energy stored in a spring

by aligass2004
Tags: energy, spring, stored
 P: 236 1. The problem statement, all variables and given/known data How much energy can be stored in a spring with k = 400N/m if the maximum possible stretch is 12cm? 2. Relevant equations U = 1/2k(x^2) 3. The attempt at a solution I tried using the above equation. U = 1/2(400)(.12^2) = 2.88.
 P: 440 This looks correct, what's your question exactly?
 P: 11 If I'm not mistaken, that's the energy of just one particle from the spring.
P: 21,399

## Energy stored in a spring

The mechanical energy is stored uniformly in the spring for the most part (assuming uniform material properties, e.g. elastic modulus), but that is the energy that would be imparted to any mass at the end of the spring (with respect to the other end) if the spring were released and pushed or pulled the mass.
 P: 236 Well I tried the answer, and it was wrong. I don't know what other equation I would use.
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P: 5,801
 Quote by aligass2004 Well I tried the answer, and it was wrong. I don't know what other equation I would use.
what units should you use for the stored energy? (You left them out).
 P: 236 It would be (N/m)(m^2) = Nm = J
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P: 5,801
 Quote by aligass2004 It would be (N/m)(m^2) = Nm = J
OK try 2.88J or 2.9J (I'm not good at significant figures) and see if the computer buys it.
 P: 440 As far as sig figs go, I think it should be 3 Joules. We only know the spring constant to one significant digit.
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 Quote by hotcommodity As far as sig figs go, I think it should be 3 Joules. We only know the spring constant to one significant digit.
Yes, I think you're right, webassign gets very picky.
 P: 236 Holy crap everyone!! I am so sorry about this problem. I was just going to try entering 3, when I noticed that I didn't put the decimal point into my original answer. BIG difference between 288 and 2.88! Sorry again!!!!!
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