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Homework Help: Combining conservation laws (momentum and energy)

  1. Apr 21, 2012 #1
    1. The problem statement, all variables and given/known data
    A 15kg block is attached to a very light horizontal spring of force constant 500 N/m and is resting on a frictionless horizontal table. It is struck by a 3kg stone travelling horizontally at 8m/s to the right, whereupon the stone rebounds at 2 m/s horizontally to the left.

    Find the maximum distance that the block will compress the spring after the collision.

    2. Relevant equations
    m1v1i + m2v2i = m1v1f + m2v2f
    ΔKE + ΔEE = 0

    3. The attempt at a solution
    Using conservation of momentum I ended up with v2 final (the 15kg block) being 2 m/s.
    Then I plugged that into 1/2mv^2 - 1/2kx^2 = 0 and solved for x.

    I got 0.346m, is this correct?
  2. jcsd
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