# Doppler effect of light problem Please assist

1. Oct 5, 2004

### stunner5000pt

There is a space shuttle service between earth and mars. Each spaceship is equipped with two identical lgihts one at the frotn and one at the rear. The spaceships travel at constnat speed u0 relative to earth such that an observer standing on earth sees the headlights of an approachin ship as green 500nm wavelength while the observer sees taillights of a departing ship from earth as red with 600 nm wavelength.

What is the value of U0/C ? What is the frequency of the lgith from the either of the lights on a spaceship according to the pilot of that ship?

too ka lot of headracking but i figured

500 = f0 (root(1+B/1-B))

and 600 = f0 (root(1-B)/(1-B))

and B = 1/11 and wavelength is 456nm (not sure about this, since the ship is aproaching then the light approaching earth would be more higher than what was really emitted fro mteh ship. so is 456 wrong??

part B)
One spaceship accelerates to new speed u relative to earth such taht one taillight of the spaceship i nfront of it apears green of wavelength 500nm. What's he value of u/c?

this follows from the first part
the answer would be altered by the real frequency of the ship's headlight.

Last edited: Oct 6, 2004
2. Oct 5, 2004

### robphy

As you've indicated in your first paragraph, wavelength is measured in nm.
However, frequency is not.

Check your system of equations again.

3. Oct 5, 2004

### stunner5000pt

thank you for pointing my typo

can yo help me with the question, however