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Physics wave question

  • Thread starter roxxyroxx
  • Start date
  • #1
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Homework Statement



a spectral line coming from a star in a binary system has a wavelength of 515.2 nm. in the lab the same spectral line would have a wavelength of 518.6 nm. what is the speed of the star in relation to earth?

Homework Equations


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The Attempt at a Solution


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Answers and Replies

  • #2
look up doppler effect, i'm not going to propose solution, because once you learn it for yourself -- I'm sure you'll figure it out in an instant (at least in a classical sense, not accounting the general relativity corrections -- there's not enough info in the problem to use that anyway).
 
  • #3
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Or you could try relativistic doppler effect.
 
  • #4
15
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Use the Dopple formula:

f'=f.V/(V+Vs)

V=c=3.10^8 m/s :speed of the radio wave.
Vs: velocity of the star (source).

U should find Vs, if it's positive then the star is moving away from the earth, otherwise it's moving closer.
 

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