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Homework Help: Light is NOT constant relative to the source.

  1. Sep 23, 2009 #1
    1. The problem statement, all variables and given/known data


    2. Relevant equations

    How do you come up with 2ud/(c^2-u^2)

    3. The attempt at a solution

    Here's my issue with this problem: I would expect that for the light from A1 to reach Earth it would be d/u-c, and the time for the light of A2 to reach earth would be d/u-c + T/2 = d/(u-c)
    + pir/u

    Therefore Delta A would be (pi)(radius)/u

    This isnt the case however, am I missing something? Shouldn't the difference in times be equal to half the period of rotation?
  2. jcsd
  3. Sep 23, 2009 #2
    shouldn't it be d/(u+c) from A1, since the star is moving towards the earth.
    If you use that you get the difference from your text.
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