Kevin R. answered • 07/20/15

Tutor

New to Wyzant
Love to learn, love to help others learn.

2 formulas for doppler shift frequency (well 8 actually)

1 for source moving toward stationary listener

Ft = [ v / (v - Vs) ] *f

1 for source moving away from listener

Fa = [ v / (v + Vs) ] *f

v is sped of sound -- 343 m/s

2Fa = Ft (frequency halved)

solve each for Vs (speed of car, source) , set 2 equations equal (Vs=Vs) f cancels

subsititute Ft = 2Fa

solve for Fa, then obtain Ft (1/2 fa).

answer is 1/3 of Vsound