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Energy stored in a spring

by aligass2004
Tags: energy, spring, stored
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aligass2004
#1
Oct31-07, 09:11 PM
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.
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hotcommodity
#2
Oct31-07, 09:23 PM
P: 436
This looks correct, what's your question exactly?
dzogi
#3
Nov1-07, 05:02 AM
P: 11
If I'm not mistaken, that's the energy of just one particle from the spring.

Astronuc
#4
Nov1-07, 07:41 AM
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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.
aligass2004
#5
Nov1-07, 02:55 PM
P: 236
Well I tried the answer, and it was wrong. I don't know what other equation I would use.
PhanthomJay
#6
Nov1-07, 03:03 PM
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Quote Quote by aligass2004 View Post
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).
aligass2004
#7
Nov1-07, 03:20 PM
P: 236
It would be (N/m)(m^2) = Nm = J
PhanthomJay
#8
Nov1-07, 03:46 PM
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Quote Quote by aligass2004 View Post
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.
hotcommodity
#9
Nov1-07, 04:29 PM
P: 436
As far as sig figs go, I think it should be 3 Joules. We only know the spring constant to one significant digit.
PhanthomJay
#10
Nov1-07, 05:38 PM
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Quote Quote by hotcommodity View Post
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.
aligass2004
#11
Nov2-07, 02:05 PM
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!!!!!
PhanthomJay
#12
Nov2-07, 03:51 PM
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Quote Quote by aligass2004 View Post
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!!!!!
Great, just when I learn how to do significant figures, the computer wasn't looking for 'em. That figures!


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