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Homework Help: Collision of billiard balls

  1. Mar 20, 2010 #1
    1. The problem statement, all variables and given/known data

    Two billiard balls, one heading north at 15.0 m/s and a second heading south at 10.0 m/s, collide head-on. Take the collision to be perfectly elastic and choose the positive direction north.

    What is the post-impact speed of the first ball
    Answer: m/s

    What is the post-impact speed of the second ball?
    Answer: m/s

    2. Relevant equations

    3. The attempt at a solution

    Don't even know where to start.
  2. jcsd
  3. Mar 20, 2010 #2
    You start by applying conservation of momentum and conservation of kinetic energy.
  4. Mar 20, 2010 #3
    But don't i need the mass in order to do that?
  5. Mar 20, 2010 #4
    They are identical billiard balls I assume, in mass and otherwise.
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