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Homework Help: Momentum Question

  1. Apr 24, 2010 #1
    A 2 kg steel ball A travelling west at 5 m s–1 collides elastically head-on with a
    stationary ball B also of mass 2 kg. Without doing any calculations, state the
    velocities (including directions) of the two balls after collision.

    Initial momentum = final momentum = 10

    I got 10/4 since I assumed it was coupled but it says that V of a is 0 and V of b is 5.
    Even so, there would be two variables; how would I solve this? Could anyone please calrify for me?

    When I did it separately I got 5 = mv(a) + mv(b)
  2. jcsd
  3. Apr 24, 2010 #2


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    Homework Helper

    You can easily state the direction, but they didn't give too much info about a and b, and well they said elastically so kinetic energy is conserved. You'll get another equation there.
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