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Balls colliding line

  1. Dec 29, 2009 #1
    Suppose there are 8 balls in line on a horizontal table.
    Another 2 balls collide them from left side(both approach together) with velocity v.
    The last 2 balls(from right) get knocked off with the same velocity as that of the balls that approached first.Why don't all the 8 balls move with a velocity v/4 or why doesnt only the last ball get knocked off with a velocity 2v?

    The collision is elastic.

    Something like this:
    00 00000000
    00000000 00
  2. jcsd
  3. Dec 29, 2009 #2


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    This only happens in an ideal case, where there is no loss in kinetic energy. It occurs because of the way the elastic compression of each ball in the pack transfers the force from the colliding balls through the pack of balls to the ejected balls. This was covered in a earlier thread:

    Last edited: Dec 29, 2009
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