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Homework Help: Simple Mass Defect Calculation

  1. Apr 22, 2012 #1
    1. The problem statement, all variables and given/known data

    Find the mass defect of O-15.

    2. The attempt at a solution

    I've see a couple different suggested ways for computing the mass defect and I want to know if I'm doing this correctly.

    Mass of O-15 = 13,975 MeV/c^2
    Proton mass = 938.3 MeV/c^2
    Neutron mass = 939.6 MeV/c^2

    D = (8Mp + 7Mn - M) = (8(938.3) + 7(939.6) - (13,975)) = 108.6 MeV/c^2
  2. jcsd
  3. Apr 22, 2012 #2
    You probably need to add 8 electron masses also, it means something at this scale unless the Mass of O-15 is without electrons.
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