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Homework Help: Particles and special relativity

  1. Oct 23, 2006 #1
    hi wondering if i could get a little help with this question

    A particle with rest mass m has kinetic energy equal to twice its rest energy. The particle decays into 2 photons which emerge in opposite directions, one travelling in the same direction as the particle before its decay. Find expressions, in terms of m for:

    (a) the momentum of the particle
    (b) the energy of each of the 2 photons

    thanks for any help.
  2. jcsd
  3. Oct 23, 2006 #2


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    What help do you want? Where is the difficulty? In other words, what have you done on this yourself?
  4. Oct 23, 2006 #3

    Meir Achuz

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    For (a), start with T=E-m=2m. Solve for E and then for p.
    For (b), LT each photon's energy in the particle's rest frame (k=m/2),
    to the frame moving with velocity v=p/E.
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