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Momentum of a proton

  • 15-10-2011 3:48pm
    #1
    Smythe
    Registered Users, Registered Users 2 Posts: 434 ✭✭


    A proton of rest mass 1.67 x 10^-27 kg is moving at a constant speed of 0.7c

    What is it's momentum?
    Using E = γmc^2 I obtained;

    E = 2.10 x 10^-10 J


    Then with;

    E^2 = (pc)^2 + (mc^2)^2 and solving for p I got;

    p = 4.88 x 10^-19

    What do you think of my attempt?


Comments

  • #2
    Morbert
    Registered Users, Registered Users 2 Posts: 3,457 ✭✭✭Morbert


    Smythe wrote: »
    Using E = γmc^2 I obtained;

    E = 2.10 x 10^-10 J


    Then with;

    E^2 = (pc)^2 + (mc^2)^2 and solving for p I got;

    p = 4.88 x 10^-19

    What do you think of my attempt?

    That is correct, but you could have used the relativistic momentum equation.

    p = γmv = 4.9 x 10^-19


  • #3
    Smythe
    Registered Users, Registered Users 2 Posts: 434 ✭✭Smythe


    Morbert wrote: »
    That is correct, but you could have used the relativistic momentum equation.

    p = γmv = 4.9 x 10^-19
    That would probably be a more sensible way to go about it.


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