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Help with conservation of kinetic energy and momentum

  1. Oct 2, 2011 #1
    1. The problem statement, all variables and given/known data

    Alpha particle mass - 4amu
    velocity alpha particle - 3.0x10^5m/s

    197Au Nucleus mass - 197amu

    Head-on elastic collision. Find the final velocity of both the particles
    2. Relevant equations

    Kinetic Energy conserved:
    1/2m1v1i = 1/2m1v1f + 1/2m2v2f

    Momentum Conserved:

    m1v1i = m1v1f + m2v2f

    3. The attempt at a solution


    For Momentum:

    4 x (3 x 10^5) = 4V1f + 197v2f
    3 x 10^5 = V1f + 49.25v2f
    V1f = 3 x 10^5 - 49.25v2f


    For Kinetic Energy

    4 x (3.0 x 10^5)2 = 4V1f2 + 197v2f2
    3.6 x 1011 = 4V1f + 197v2f
    9 x 1010 = V1f + 49.25v2f

    Subbing in one for the other


    9x 1010 = (300,000 - 49.25v2f)2 + 49.25v2f


    The v2f and V1f values I get doesn't work out



    Thanks in advance for your help.
     
  2. jcsd
  3. Oct 3, 2011 #2

    Redbelly98

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    Staff Emeritus
    Science Advisor
    Homework Helper

    That last v2f is really v2f2, right?

    What values do you get? It looks like the right approach.

    p.s. Welcome to Physics Forums!
     
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