Frequency of a car horn passing by

Question

Coincidentally the horn on your car, which you sound as you narrowly miss the flautist in Problem 9.7, also gives a constant 300 Hz tone. What frequency does the flautist hear before and after you pass them?

(previously asked)

9.7. After giving an intense performance, a confused and disoriented flautist has wandered onto the motorway! They are playing a constant 300 Hz tone on their flute and are essentially stationary. If you are driving along the motorway at 100 km h^-1 (27.8 m s^-1), what is the frequency you hear from the flautist's instrument before you pass them, and after you pass them? (c_air = 343 m s^-1)

Answer 1

The formula needed is f´=[(v+v_o)÷(v-v_s)]f to find the frequency before and f´=[(v-v_o)÷(v+v_s)]f to find frequency after. f´ is what you're looking for, v is speed of sound, v_o is speed of observer, v_s is speed of source, and f is the frequency that the source of outputting.

I hope this sparks some ideas!