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Homework Help: 1 dimensional elastic collision

  1. Nov 1, 2008 #1
    A 0.415-kg hockey puck, moving east with a speed of 2.65 m/s, has a head-on collision with a 0.910-kg puck initially at rest.
    Assuming a perfectly elastic collision, what will be the velocity of each object after the collision?
    The solution is:

    v ' (lighter puck) , v' (heavier puck) = -0.990, 1.66 m/s, respectively.

    My question is, wouldn't the lighter puck be expected to have a higher velocity magnitude than the heavier puck following the collision?
  2. jcsd
  3. Nov 2, 2008 #2
    For perfectly elastic collisions, kinetic energy is conserved.

  4. Nov 2, 2008 #3
    Ok, i made that assumption when solving the problem.

    I'm asking conceptually, wouldn't the heavier object be expected to move with a smaller velocity magnitude?
  5. Nov 2, 2008 #4
    Sorry, I didn't read your question properly :redface:

    That will only be the case if the initial kinetic energy is divided equally between the two objects, i.e. when after the collision


    so that

  6. Nov 2, 2008 #5
    Ah gotcha. Thanks for the help! :smile:
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