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Homework Help: Block held against a spring going up a frictionless plane

  1. Jan 26, 2009 #1
    1. The problem statement, all variables and given/known data
    A 3 kg block is held against a spring (k=580nt/m) at the bottom of a frictionless 25 degree incline. The spring is compressed 0.18m. How far along the incline does the block go when released.

    2. Relevant equations

    3. The attempt at a solution
    So far the only thing I've been able to do was calculate the velocity which i got to be 1.65m/s if I did it correctly.

    Usp= 1/2 * 580 * .18^2
    = 9.396

    then I did this equation but I didn't know exactly what h was that I was trying to calculate. I think i just ended up calculating how much the spring was compressed and I already knew that.

    9.396 + (1/2)(3)(0) = (3)(9.8)(h) + (1/2)(3)(1.654^2)
    9.396 = 29.4h + 4.103
    h = .18
    Last edited: Jan 26, 2009
  2. jcsd
  3. Jan 26, 2009 #2
    did I not supply enough information?
  4. Jan 26, 2009 #3


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    Homework Helper

    Welcome to PF.

    The PE at the bottom should really give you your height shouldn't it?
  5. Jan 26, 2009 #4


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    Science Advisor
    Homework Helper
    Gold Member

    The speed at what position?

    Actually, you don't need to find any speed to solve the problem. At the beginning and at the end of the motion (at the max height) the speed is zero.
    You could simply do

    9.396 J = 3 * 9.8 * h

    find h and then use the angle to find the distance along the incline.
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