1. Limited time only! Sign up for a free 30min personal tutor trial with Chegg Tutors
    Dismiss Notice
Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Homework Help: Particle decays

  1. Oct 8, 2005 #1


    User Avatar

    I've been trying to use energy and momentum conservation in this problem but it didn't work out or I got a quadratic equation and got 3 different answers. Can anyone help me please. Here is the problem

    The Gorgon ( rest mass of 3000 MeV/c^2) decays into a photon (i.e, a particle of light) and Lexicon (rest mass of 1800 MeV/c^2).

    The Gorgon was initially at rest. The photon is emitted in the -x direction and the Lexicon is in the +x direction. Find the energy of the photon and the final velocity of the Lexicon.

    Thanks a lot
  2. jcsd
  3. Oct 8, 2005 #2


    User Avatar
    Staff Emeritus
    Science Advisor

    Please show what you have done.

    Think - Conservation of energy and conservation of momentum.

    The momentum of a photon, p = E/c

    Remember there is rest energy and kinetic energy, so total energy must be conserved, and momentum.
  4. Oct 9, 2005 #3


    User Avatar

    I have Eg = Ep + El and the same thing for p

    also E = square root of [(pc)^2 + (mc^2)^2]

    and pc of photon will be equal -pc of elicon.

    Substitute both of the above into the conservation of energy equation. I only have one unknow which is p of photon. But then I got a quandratic equation with 3 different answers. I dunno what to do next.

Share this great discussion with others via Reddit, Google+, Twitter, or Facebook