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Oblique Collisions

  1. Apr 17, 2012 #1
    In an oblique collision (when one object hits another object of IDENTICAL mass at a slight angle the two objects move at right angles to each other.

    my book says

    p2 = p12 + p22

    For momenum conservtation:

    p= p1+ p2

    apparently these equations can only be consistent of the collision occurs at right angles. why?
     
    Last edited: Apr 18, 2012
  2. jcsd
  3. Apr 18, 2012 #2

    haruspex

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    These are vectors, right?
    p.p = (p1+p2).(p1+p2) [2nd equn]
    = p1.p1 + 2.p1.p2 + p2.p2
    = p.p + 2.p1.p2 [1st equn]
    Hence p1.p2 = 0
     
  4. Apr 18, 2012 #3
    where has p2.p2 gone in the final line
    surely the final line should be
    = p1.p2 + p2.p2, no?
     
    Last edited: Apr 18, 2012
  5. Apr 18, 2012 #4

    haruspex

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    1st equn says p.p = p1.p1 + p2.p2
    To get from my second line to my third line, use this to substitute p.p for p1.p1 + p2.p2.
     
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