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: Relation between a photon's energy and momentum

  1. Feb 23, 2013 #1

    For part b), I can see that, as [itex]p = \frac{E}{c}[/itex], then a photon with twice the momentum must have twice the energy. However, I cannot see the answer to part a). My book states that [itex]k_2 = 4k_1[/itex], but I would have thought that, as per the answer to b), the KE is just twice that of the other, not four times?
  2. jcsd
  3. Feb 23, 2013 #2


    User Avatar
    Science Advisor
    Gold Member

    The particle in part A is a proton, not a photon.
    And since it travelling at a speed much lower than c you can just use classical mechanics.
  4. Feb 23, 2013 #3
    Oh wow... All this reading about photons has me seeing the word everywhere -_-

    Thank you very much :)
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook