# Homework Help: Special relativity noob problem 2, Dopler shift.

1. Nov 16, 2008

### -Vitaly-

1. The problem statement, all variables and given/known data

By 2025 a spaceship shuttle service operates between the Earth and Mars. Each
spaceship is equipped with identical mono chromatic head and tail lights, and their cruising speed v relative to earth, is such that the headlight of a homeward-bound spaceship appears green ( lambda = 500 nm) and the tail-light of a departing spaceship appears red(lambda = 600 nm).(i) What is v/c ?(ii) What is the wavelength of the headlight of an earth-b ound spaceship is observed froman outward b ound one?

2. Relevant equations

http://hyperphysics.phy-astr.gsu.edu/hbase/relativ/reldop2.html" [Broken]

3. The attempt at a solution
I have no idea where to start.

Last edited by a moderator: May 3, 2017
2. Nov 17, 2008

### tiny-tim

Hi -Vitaly-!

The two lights are the same colour, but they look different because of the Doppler shift.

Just plug in the equations, and see what happens!