1. The problem statement, all variables and given/known data How fast would a motorist have to be traveling for a yellow (l = 595 nm) traffic light to appear green (l = 550 nm) because of the Doppler shift? 2. Relevant equations v=[(c)(f0/fs)2-c] / [(f0/fs)2+1] 3. The attempt at a solution v= Speed of motorist c= Speed of light f0= Observed wavelength (green, (5.5x10^-7 m) fs= Source wavelength (yellow, (5.95x10^-7 m) First of all, am I using the correct equation? Because i'm almost certain my work is correct, since after plugging in the above known numbers, i get 2.35x10^7 m/s for an answer, but this answer is not correct. Any help would be greatly appreciated!