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Height with EPE question.

  1. Jan 28, 2009 #1
    1. The problem statement, all variables and given/known data
    A .250 kg block on a vertical spring with a spring constant of 5.00 x 10(3) N/m is pushed downward, compressing the spring .100 m. When released, the block leaves the spring and travels upward vertically. How high does it rise above above the point of release?

    Mass = .250 kg
    Distance = .100m
    Spring Constant/K = 5.00 x 10(3) N/m or 5000 N/m

    2. Relevant equations
    Have to find EPE I think, EPE = 1/2 K(^x)2....the ^ is a triangle which in this equation is change in length.
    Maybe use mgh

    3. The attempt at a solution

    I got EPE which was 25. I think that to find h you can use formula mgh. I forgot how to do this but I recall doing something like (.250)(9.81)(h), 2.45(h), and you take the square root of 2.45 and that is how you get h. Then in this problem h would = 1.60m. I really think this is wrong but it was all I could think of.

    Can someone please help me find the height? Or if I have the correct method please reply and tell me I did it right(don't think I did though)

    Thank You
    ~Patrick
     
    Last edited: Jan 28, 2009
  2. jcsd
  3. Jan 28, 2009 #2

    Kurdt

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    All you have to do is equate the spring potential energy with the gravitational potential energy to find the height.
     
  4. Jan 28, 2009 #3
    So PE = the GPE and divide like...2.45(h) = 25..25/2.45...h = 10.2m

    Is this correct?

    Thank You
    ~Patrick
     
    Last edited: Jan 28, 2009
  5. Jan 28, 2009 #4

    Kurdt

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    Equate just means setting one thing equal to the other. In your question you have set:

    [tex] \frac{1}{2}kx^2 = mgh[/tex]

    With some algebraic manipulation you can make h the subject and plug in the numbers.
     
  6. Jan 28, 2009 #5
    Okay, so I had done that, I'm pretty sure 10.2m is the answer than, can you confirm that though?
     
  7. Jan 28, 2009 #6

    Kurdt

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    Yes, that looks good to me.
     
  8. Jan 28, 2009 #7
    Okay, thank you very much.
     
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