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Homework Help: Confusion in special relativity - total newbie

  1. Mar 8, 2008 #1
    I'm sure it's a stupid question but this is my first crack at SR so help would be great.

    1. The problem statement, all variables and given/known data
    Frame S' has a speed of 0.7c along the x axis relative to frame S. Clocks are adjusted so t=t'=0 at x=x'=0.

    An even occurs in S at t1 = 3 x 10^7s at x1 = 40m. At what time does the event occur in S'?

    2. Relevant equations
    [tex]\beta = 0.7[/tex]
    [tex]\gamma = 1.4003[/tex]
    [tex]x' = \gamma (x - t\beta c)[/tex]

    3. The attempt at a solution

    [tex]x' = \gamma (x - t\beta c) = (1.4003)(40 - (3 * 10^7)0.7 c) = -32.21m[/tex]

    Is this answer correct? It seems to me it can't possibly be right! What am I doing wrong?
  2. jcsd
  3. Mar 8, 2008 #2

    Shooting Star

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    Homework Helper

    Why do you think this cannot be right? Think of where the origin of S' is wrt S when the event happens.

    BTW, you have a direct formula for finding the time, which is the actual question.
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