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Homework Help: Honors Physics Momentum Problem

  1. Jan 11, 2009 #1
    1. The problem statement, all variables and given/known data
    A .45kg ice puck, moving east with a speed of 3 m/s has a head-on collision with a .9 kg puck initially at rest. Assuming a perfectly elastic collision, what will be the speed and direction of each object after the collision?

    M1 = .45kg
    M2 = .9kg
    V1 = 3m/s
    V2 = 0m/s

    Perfectly elastic collision means Kinetic Energy and Momentum are conserved.

    2. Relevant equations

    KE = 1.2 * m * v2
    P = m * v

    3. The attempt at a solution

    KEI = KEF (Initial KE = Final KE)
    1/2 * m1 * v12 + 1/2 * m2 * v22 = 1/2 * m1 * (v1')2 + 1/2 * m2 * (v2')2


    m1 * v1 + m2 * v2 = m1 * v1' + m2 * v2'

    I don't really know where to go from here or if this is the right start...

    Thanks in advance
  2. jcsd
  3. Jan 11, 2009 #2
    You do have the right start. The rest is just really ugly algebra and moving things around.

    Also, there is no such thing as kinetic energy conservation. Kinetic energy is not conserve, but energy is conserve. It just happens that there is no potential energy in your problem.
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