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[Relativity] Energy and momentum question

  1. Jan 3, 2013 #1
    1. The problem statement, all variables and given/known data

    Write down a relation between the total relativistic energy, mass and momentum of a
    particle. An antiproton has a total energy of 5.00 GeV. Calculate its momentum and its
    speed.



    2. Relevant equations

    E = γmc^2
    E = (cp)^2 +(mc^2)^2
    p = γmv

    3. The attempt at a solution

    I've tried subbing everything in and playing around with the algebra but I cant get an expression entirely in terms of v or p.
    Also how do you get the proper math equations on here? Are the tags [itex]?
     
    Last edited: Jan 3, 2013
  2. jcsd
  3. Jan 3, 2013 #2

    Dick

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    Homework Helper

    Here's a TeX tutorial. https://www.physicsforums.com/showpost.php?p=3977517&postcount=3 Try just using the second equation. You know E and you can look up the mass of the proton. That will get you p.
     
  4. Jan 3, 2013 #3
    Sorry I should have said, this is a question from an exam a few years ago and it doesn't mention the mass of the proton anywhere in the entire paper. Is there a way to get the answer without knowing m?
    Cheers for the tutorial!
     
  5. Jan 3, 2013 #4

    Dick

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    No, you need to know something else besides just the energy.
     
  6. Jan 3, 2013 #5

    jtbell

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    Staff: Mentor

    And make that E^2, not E, on the left-hand side. :wink:
     
  7. Jan 3, 2013 #6

    Dick

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    Good point!
     
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