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Doubt about relativity

  1. Sep 8, 2011 #1
    Doubt about relativity!!

    I am a noob! Forgive me if it sounds too stupid!

    Let me say, I am in CERN right now at the LHC.
    I fire a proton at 0.9c in one direction. While this happens, I also fire another proton at 0.5c in the opposite direction. Both the measurements were done considering the lab as a reference frame.

    The problem is, what's the speed(or velocity) of either proton relative to one another??
  2. jcsd
  3. Sep 8, 2011 #2


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    Gold Member

    Re: Doubt about relativity!!

    It will be given by [itex]v' = {{v_1 + v_2}\over{1+{{v_1v_2}\over{c^2}}}}[/itex]

    Numerically either proton will see the other shoot off at .966c

    Formally you consider one of the proton's rest frame and send the lab traveling off at 0.9c/0.5c and then the other proton is shot off at 0.5c/0.9c from the lab frame.
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