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Homework Help: Perfectly Elastic Collision

  1. Dec 2, 2007 #1
    [SOLVED] Perfectly Elastic Collision

    1. A particle of mass m and speed V collides at a right angle with a very massive wall in a perfectly elastic collision. What is the magnitude of the change in momentum of the particle?

    2. P before colision = P after collision.

    3. I think the answer is zero. Is this correct?

    Thanks in advance! :)
  2. jcsd
  3. Dec 3, 2007 #2
    sorry, wrong
    Last edited: Dec 3, 2007
  4. Dec 3, 2007 #3
    Well, it does change direction. :) So it's -1 x P (for the new velocity).
  5. Dec 3, 2007 #4
    Momentum prior to collision: [tex]m\vec{v_1}[/tex]
    Momentum after collision: [tex]m\vec{v_2}[/tex]

    [tex]\vec{v_1}=v_x \hat{x}[/tex]
    [tex]\vec{v_2}=-v_x \hat{x}[/tex]

    [tex]\Delta{p}=m(v_x\hat{x}- - v_x\hat{x})[/tex]
    [tex]\Delta{p}=2m v_x \hat{x}[/tex]

    Since it asks for magnitude:

  6. Dec 3, 2007 #5
    Sorry, bill is right, i was wrong.
    Perfectly elastic collision occurs in isolated systems tho no? so you can't really consider this a collision, this is like magnitude of velocity in equals to magnitude of velocity out.
  7. Dec 3, 2007 #6
    Thank you!! That makes so much more sense!
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