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Homework Help: Minium Electric Potential

  1. Aug 3, 2010 #1
    1. The problem statement, all variables and given/known data

    A plutonium-239 nucleus, initially at rest, undergoes alpha decay to produce a uranium-235 nucleus. The uranium-235 nucleus has a mass of 3.90 * 10-25 kg, and moves away from the location of the decay with a speed of 2.62 * 105 m/s.

    Determine the minimum electric potential difference that is required to bring the alpha particle to rest.

    2. Relevant equations



    3. The attempt at a solution

    mu-235 = 3.90 * 10-25 kg
    vu-235 = 2.62 * 105 m/s
    map = 6.65 * 10-27 kg
    qap = +2e = +2(1.60 * 10-19 C) = +3.20 * 10-19 C

    |pu-235| = |pap|
    mu-235vu-235 = mapvap
    vap = mu-235vu-235/map
    vap = (3.90 * 10-25 kg)(2.62 * 105 m/s)/(6.65 * 10-27 kg)
    vap = 1.536541353 * 107 m/s
    Ek = 1/2mapvap2
    Ek = 1/2(6.65 * 10-27 kg)(1.536541353 * 107 m/s)2
    Ek = 7.85018977 * 10-13 J
    Ek = qapVstop
    Vstop = Ek/qap
    Vstop = (7.85018977 * 10-13 J)/(3.20 * 10-19 C)
    Vstop = 2.45 * 106 V

    The minimum electric potential difference that is required to bring the alpha particle to rest is 2.45 * 106 V.
     
    Last edited: Aug 3, 2010
  2. jcsd
  3. Aug 3, 2010 #2
    I posted my work/answer. I just want to confirm that it is in fact right.
     
  4. Aug 3, 2010 #3

    diazona

    User Avatar
    Homework Helper

    You're not being ignored, sometimes it just takes a while ;-) Anyway, the procedure you used looks reasonable, and I don't see any obvious errors in what you've done.
     
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