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Homework Help: Calculate KE, E, p and f for proton.

  1. Oct 13, 2012 #1
    1. The problem statement, all variables and given/known data
    photon(0 MeV), electron(0.511MeV), photon(938 MeV) have wavelength of 2.0*10^-15 m, 2.0pm. Calculate their kinetic energy, total energy, momentum, all in MeV, and velocity and frequency.

    2. Relevant equations
    E = K + mc^2
    E^2 = (pc)^2 + (mc^2)^2

    3. The attempt at a solution
    for photon:
    K 0.621 MeV
    E 0.621 MeV
    p 0.621 MeV/c
    v 3*10^8 m/s
    f 1.5*10^20 Hz

    for electron:
    K 0.292 MeV
    E 0.803 MeV
    p 0.62 MeV/c
    v 0.77 c
    f 1.94*10^22 Hz

    for proton:
    K 0.0002 MeV
    E 938.0002 MeV
    p 0.62 MeV/c
    v 6.6*10^-4 c = 1.98*10^5 m/s
    f 2.2*10^23 Hz

    I am a little bit not sure about my results regarding proton's. Any help verifying my answers will be appreciated because I don't have answer for this problem.
  2. jcsd
  3. Oct 13, 2012 #2
    You're right, but your rounding is a little weird. You have only two digits for p, but then you have 7 digits for E. With any reasonable rounding, you would have 2/3 digits for E and just get 0 for K.
  4. Oct 13, 2012 #3
    thank you.
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