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Einstein Velocity Addition

  1. Feb 25, 2015 #1
    Lets suppose we used Einstein Velocity Addition equation and we found a result this is the same for every observer isnt it ?
     
  2. jcsd
  3. Feb 25, 2015 #2

    Nugatory

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    I'm having some trouble understanding your question. What exactly do you expect to be the same for all observers?
     
  4. Feb 25, 2015 #3
    An observer O observer o observes two objects letc call them a and b ad their speed a 0.5c and b 0 c so relative velocity is 0.5c İts for observer a than lets suppose theres another observer I am asking this another observer et call z will calculate relaitve speed 0.5 isnt it ? (Relative speed between A and B)
     
  5. Feb 25, 2015 #4

    HallsofIvy

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    Yes. If observers x and y both observe objects A and B, determine the speeds of A and B relative to themselves, then calculate the speed of A relative to B, they will get the same answer.
     
  6. Feb 25, 2015 #5

    Nugatory

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    If A is moving at .5c relative to B, then A will be moving at .5c relative to all observers at rest relative to B.

    If B is moving at some non-zero speed q relative to some third observer Z, then A's speed relative to Z will not be q+.5c and Z's measurement of the difference between the speed of A and B will not be .5c.
     
  7. Feb 25, 2015 #6

    jtbell

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    Have you tried calculating it yourself? Suppose observer z is traveling at velocity 0.25c relative to observer o. Let va' and vb' be the velocities of a and b relative to z.

    (a) What do you get for va' and vb' ?

    (b) What do you get for the relative velocity vab' = (va' - vb') / (1 - va'vb'/c2) ?
     
    Last edited: Feb 25, 2015
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