Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

A question in special relativity

  1. Feb 1, 2009 #1


    User Avatar

    A particle of mass m moves in a center of mass frame of reference with a momentum p=2m. The center of mass moves with a speed v along the axis in the frame of reference of the laboratory. What's the angle of the particle in the frame of reference of the laboratory.

    What i think I have to do is to calculate the speed of the particle in the laboratory frame of reference, than it is just a simple trigonometric calculation. But I don't really know how to do this.
  2. jcsd
  3. Feb 2, 2009 #2


    User Avatar
    Science Advisor
    Homework Helper

    Hi mck! :smile:
    uhh? :confused: that's v. :wink:

    Hint: momentum is the x,y,z components of 4-momentum, which is a 4-vector which transforms exactly the same way as an (x y z t) 4-vector.

    So split p into pcosθ and psinθ, and transform them separately. :smile:
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook