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Homework Help: Relative Velocity and vectors

  1. Oct 14, 2007 #1
    I'm having trouble picturing the following problem.

    In a given inertial frame, two particles are shot out simultaneously from a given point, with equal speed u, in orthogonal directions.

    a) Without using 4-vectors show that the speed of each particle relative to the other is given by:

  2. jcsd
  3. Oct 14, 2007 #2

    Doc Al

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    Staff: Mentor

    Call the given frame S'. In that frame, imagine that one particle (B) is moving with velocity +u along the y-axis; the other particle (A) is moving with velocity -u along the x-axis.

    Now view things from the frame of particle A, which you can call S. Note that S' moves with speed +u along the x-axis in frame S. (The usual set up for Lorentz transformations.)

    How do velocities transform in special relativity?