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Homework Help: Doppler effect of light

  1. Sep 22, 2009 #1
    1. The problem statement, all variables and given/known data
    An astronaut is said to have tried to get out of a traffic violation for running a red light (lambda= 670nm) by telling the judge that the light appeared green (lambda= 540nm) to her as she passed by in her high powered transport. If this is true, how fast was the astronaut going?

    2. Relevant equations

    Lambda= c(Tperiod)

    3. The attempt at a solution
    5.40X10-7m= 3.00x108( T)
    T= 1.8x10-15sec

    Im not sure if this is the correct approach but once you get the time how do you get the speed?

    2. Relevant equations

    3. The attempt at a solution
  2. jcsd
  3. Sep 22, 2009 #2


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    Homework Helper
    Gold Member

    Hi Jessicah, welcome to PF!:smile:

    Well, since this is a problem on the relativistic Doppler effect, you might try reading about the effect in your textbook and finding the equation for Doppler shift....:wink:
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