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.
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.
As far as sig figs go, I think it should be 3 Joules. We only know the spring constant to one significant digit.
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!