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: Quantum physics- annihilation question

  1. Feb 23, 2009 #1
    So I'm looking at my notes, and there's a section on annihilation. It explains that in a particle/ anti-particle collision, momentum is conserved. In the problem, an electron with velocity= 8 x 10^6 m/s collides with a positron with velocity 3 x 10^6 m/s, producing two photons. The equation was set up like this

    2mc² + Ek + Ek = 2hf

    Except instead of keeping the Ek's separate for the electron and the positron, they put them together as one Ek, adding the velocities and the masses. Why would you do this?
  2. jcsd
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook

Can you offer guidance or do you also need help?
Draft saved Draft deleted