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Calculation of momentum of relativistic particles

  1. Apr 20, 2012 #1
    A particle of mass M decays at rest into a massless particle and another particle of mass m. The magnitude of the momentum of each of these relativistic particles is:

    2. Relevant equations

    E = γmc2; p=γmv

    3. The attempt at a solution
    Pf-Pi = 0; but the particle is at rest, so pi = 0; and the momentum of massless particle = 0;
    unable to start up with exact condition. Tried equating initial and final energies also, but not getting the right answer. Please help.
  2. jcsd
  3. Apr 20, 2012 #2

    George Jones

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    This isn't correct. Look in your notes and/or text for the relationship between energy and momentum for a massless particle.
  4. Apr 20, 2012 #3
    No, I tried the relation E2 = m2c4+p2c2 also, am not getting right answer. There are no explanations of this in my text graduation text books. These are pg level questions.

    I did substitute E2 = M2c4 (initial energy) and onto r.h.s, p2c2+m2c4+p2c2 - p2c2 is the kinetic energy of the massless particle and m2c4+p2c2 for the particle of mass m.

    Please give a solution if possible, am taking so much time to google n check. I am already running out of time for my entrance exam next week.