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Kinetic energy of a recoiling nucleus

  1. Mar 1, 2009 #1
    A Fe nucleus at rest emits a 14.0-keV photon. Use conservation of energy and momentum to deduce the kinetic energy of the recoiling nucleus in electron volts. (Use Mc2 = 8.60E-9 J for the final state of the Fe nucleus.)



    what I have so far is...

    E = pc because E >> photon rest energy , which = 0 eV

    P = E/C = 7.476 E-24

    P1 = P2

    I'm not sure what to do next.

    Thanks in advance for the help!
     
  2. jcsd
  3. Mar 1, 2009 #2

    malawi_glenn

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    what is the relation between Energy and kinetic energy in special relativity? And what is the relation between energy, momentum and mass in special relativity?
     
  4. Mar 1, 2009 #3
    Relation between kinetic energy and total energy in special relativity is...
    E = K + mc2
    Relationship between mass, energy and momentum is...
    E2 = P2C2 + (mc2)2
     
  5. Mar 1, 2009 #4

    malawi_glenn

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    great, then can you find, from these two, a relation between momentum, mass and kinetic energy?
     
  6. Mar 1, 2009 #5
    is this valid?

    (K+MC2) = P2C2 + (MC2)2

    then isolate K?
     
  7. Mar 2, 2009 #6

    malawi_glenn

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    you forgot to square the left-hand side ...
     
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