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Homework Help: Conservation of Energy Problem involving a spring

  1. Nov 16, 2008 #1
    1. The problem statement, all variables and given/known data
    a block is held 1.3m above a spring and is dropped.The spring compresses 6cm before sending the ball into the air. How fast is the ball going when it hits the spring? What is the spring constant? How high in the air does the ball go after hitting the spring?

    2. Relevant equations

    3. The attempt at a solution
    i can use the following to get the velocity where Y=1.3m and the masses cancel out
    M g Y = (1/2) M V^2
    To find the k i think i need to use the following equation:
    (1/2) M V^2 + M g X = (1/2) kX^2
    but i have 2 unknowns M and k iam stuck what to i do?
  2. jcsd
  3. Nov 17, 2008 #2


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    Science Advisor
    Homework Helper

    Yup, you're absolutely right … you do need to know the mass of the ball!! :biggrin:

    I can only suggest you calculate k as a multiple of M. :frown:
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