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Ratio kinetic energy of alpha particle / kinetic energy of proton

  1. Apr 21, 2009 #1
    1. The problem statement, all variables and given/known data
    A photon and alpha particle are accelerated from rest through the same potential difference.
    After acceleration what is the ratio kinetic energy of alpha particle / kinetic energy of proton?

    2. Relevant equations
    I guess I have to use eV = 1/2mv^2

    3. The attempt at a solution
    I dont know what value have to be used in place of e in equation eV = 1/2mv^2
    the mass of alpha particle is approximately 4 times of photon and that's all i know
    I guessed the answer as 4 but the answer was 2
    I think there is something to do with the velocity of alpha particle and photon but i'm stucked can not think of anything..
  2. jcsd
  3. Apr 21, 2009 #2
    An alfa particle has two protons, so that's twice the charge of one proton.
  4. Apr 21, 2009 #3
    Thanks a lot! So i didnt have to know the exact charges but the ratio
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