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Homework Help: Nuclear physics problem

  1. May 7, 2012 #1
    1. The problem statement, all variables and given/known data
    Calculate the energy released from the following reaction:-
    2(H) ---> He [mass number for H = 2, atomic number for H = 1, mass number for He = 4, atomic number for He = 2]
    Data: the mass of the H in the reaction = 2.0242 u, and its kinetic energy = 925 M.ev
    and the mass of He = 4.0015 u

    2. Relevant equations
    E = mC^2
    minimum energy required to split nucleons = Δm * 931
    mass of nucleus = (Number of protons * mass of protons) + (number of neutrons * mass of neutrons)

    3. The attempt at a solution
    i really have no idea how this is done but the only thing i can think of is E = (difference between the masses) * C^2
    so 1.9773 * 3 * 10^8 = 593190000 ??
  2. jcsd
  3. May 7, 2012 #2
    you need to balance the reaction equation out so that you have basically

    2(mhydrogen)= 1(mass of helium) + Δm

    then you can calculate the difference in mass.
    I can see one mistake and that is that you have used the value for C instead of C^2.
    Also note that the hydrogen has an initial kinetic energy I believe so don't forget to add that
  4. May 7, 2012 #3


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    The nuclear mass also includes the binding energy, that is, the energy that is released when the nucleus splits.
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