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Homework Help: Conservation of momentum basics

  1. May 13, 2010 #1
    Two baseballs undergo a head-on collision. Ball 1 is twice as heavy as ball 2. Ball 1 is traveling at an initial speed of v1, while ball 2 had an initial speed of v2. Elastic collision. If ball 1 travels at a speed of 7/5v1 after impact, what is the speed of ball 2?

    Conservation of momentum led me to this equation:

    v2 - 1.8v1 = vf

    (vf is the velocity of ball 2)

    The answer is 1.6v1 = 2v2

    I know there is some basic idea that i am missing...
  2. jcsd
  3. May 14, 2010 #2


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    Homework Helper

    Elastic collision, so kinetic energy is conserved as well.
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