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Homework Help: Determine the ratio of the electron's speed

  1. Jul 15, 2005 #1
    Determine the ratio of the electron's speed over that of the proton at the end of their respective trajectories? KE = 5.29keV

    My question is do I use the kinetic energy to get velocity of electron then proton separately, and afterwards divide the results to obtain the ratio?
  2. jcsd
  3. Jul 15, 2005 #2
    That's what I would do.
  4. Jul 15, 2005 #3
    electron: m, v
    proton: M, u

    mv²/2 = Mu²/2
    mv² = Mu²
    v²/u² = M/m
    v/u = sqrt(M/m) = sqrt(1836) = 42.85

    (valid for v << c)
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