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Relativistic Velocity Addition

  1. Oct 17, 2011 #1
    1. The problem statement, all variables and given/known data

    relative to A, B is moving towards A at a speed of 0.4c. Farther out C is moving towards A at a speed of 0.5c. all motion is along the x axis

    how fast is C moving relative to B?

    2. Relevant equations

    U = (U' + V) / 1+ VU'/c^2

    3. The attempt at a solution

    0.4c- 0.5c / 1 - (0.4c * 0.5c) / c^2 = 0.125

    C is moving at c/8 towards B

  2. jcsd
  3. Oct 18, 2011 #2


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    Gold Member

    As the problem is stated I'm not sure if B and C are heading in the same direction or heading towards each other. All we know for sure is that both B and C are moving towards A.
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