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Homework Help: Work done by a spring

  1. Feb 28, 2010 #1
    1. The problem statement, all variables and given/known data

    http://img205.imageshack.us/img205/7536/capturebb.jpg [Broken]

    i am stuck on part c

    how do i find work with out using the spring constant

    2. Relevant equations

    work equals force parallel times displacement at which the force is acted during...

    Work done by spring = .5 kx^2
    Work = delta K

    but delta K = 0 because the table top is frictionless

    Work = delta U
    delta U = 0 in this situation correct?

    3. The attempt at a solution

    so I'm stuck...

    i think it might be zero but .5 kx^2 would not give zero now would it...
    Last edited by a moderator: May 4, 2017
  2. jcsd
  3. Feb 28, 2010 #2


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    The work done on the block by the spring is equal to the change in KE of the block.
  4. Feb 28, 2010 #3
    hmmmmmmmm.... so then.... um.....
  5. Feb 28, 2010 #4
    ok thanks
  6. Feb 28, 2010 #5
    wait so to find the spring constant...

    is delta U = delta K = W = .5 kx^2

  7. Feb 28, 2010 #6
    - (Mg)/(2h)
  8. Feb 28, 2010 #7


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    0.5 kx^2 = 0.5 Mv^2.
    From the given data you can find v.
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