Question

You are in a car traveling at 25.6 m/s. A second car is moving toward you at the same speed. Its horn is sounding at 482 Hz. What frequency do you hear to two decimal places?

Answer 1

Answer: Let the speed of sound equal 331 m/s

f = f0 ( (V ± Vo) / V) observer moving

f = 482 (331 + 25.6) / 331 = 519 /s (observer moving towards source)

f = 519 (331 / (331 - 25.6) = 563 / s (source moving towards observer)

Check: For both moving:

f = f0 ((331 + 25.6) / (331 - 25.6)) = 1.17 f0 = 482 * 1.17 = 563 / s