Posted by **tasha** on Monday, June 18, 2007 at 4:09pm.

At the Indianapolis 500, you can measure the speed of cars just by listening to the difference in pitch of the engine noise between approaching and receding cars. Suppose the sound of a certain car drops by a factor of 2.40 as it goes by on the straightaway. How fast is it going? (assume speed of sound is 343 m/s).

I don't know where to start. I tried setting frequency2 = x(frequency1), where x=-2.4, but I don't know. Does anyone have suggestions? Thanks

I think I would use the doppler formula.