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Homework Help: 2D Collision

  1. Feb 13, 2008 #1
    1. The problem statement, all variables and given/known data
    Ok, I'm making an algorithm to calculate some stuff, and meanwhile, i needed to compute a 2D collision between 2 particles of same mass.

    To work that out, I needed to change referential to Mcenter. The problem was there...

    2. Relevant equations
    Vcm=(v1+v2)/2 (m1=m2)
    velocity addition by Galileo
    3. The attempt at a solution
    ok, Vcm=(v1+v2)/2
    so, v1cm=v1-Vcm=v1-(v1+v2)/2=(v1)/2-(v2)/2
    in the same way:

    Now, the problem is: this too equations are L. Dependent, that means the matrix related to it isn't invertible, so, after i calculate the Vfinal in CM referencial, i can't change it to lab referential.
    1. The problem statement, all variables and given/known data

    2. Relevant equations

    3. The attempt at a solution
  2. jcsd
  3. Feb 13, 2008 #2

    Doc Al

    User Avatar

    Staff: Mentor

    Why not? Just do the reverse of what you did to get to the CM frame: Instead of subtracting (V1 + V2)/2, add it.
  4. Feb 13, 2008 #3
    ah, duh, yeah

    Tks Doc Al
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