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Finding elastic constant given mass and elongation

  1. Feb 26, 2009 #1
    1. The problem statement, all variables and given/known data
    I'm doing a lab where a known mass is suspended by a spring. All that is known is the mass of the weight used and the length of the elongation of the spring, and I need to find the elastic potential energy of the spring and the spring constant, K.

    2. Relevant equations
    (formatted text links aren't clicking for me?)
    Elastic PE = 1/2Kx^2--x normally applies to the elongation of the spring though it is extending in the y direction in this case

    Gravitational PE = 9.81mh

    GPE + EPE = Total PE/KE (energy is assumed to be conserved)

    3. The attempt at a solution
    The problem is I have two variables and no way I can see to substitute for one of them to simplify the equation, so I don't know how to isolate a spring constant or the elastic potential energy.
  2. jcsd
  3. Feb 26, 2009 #2


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    Homework Helper

    You need the other spring formula, F = kx.
  4. Feb 26, 2009 #3
    Ah, that should help. is that force found with Mass*g*x?
    Thanks for the help thus far.
  5. Feb 26, 2009 #4


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    Homework Helper

    The F is mass*g.
    Solve for k.
  6. Feb 26, 2009 #5
    lol you're right-- after I thought about it, I realized it was just m*g. I'll be able to finish it up , and now I'm sure you want to get to some more questions so have a good night;)
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