# physics

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A person with perfect pitch sits on a bus bench listening to the 444 Hz horn of an approaching car. If the person detects a frequency of 480 Hz, how fast is the car moving?

• physics -

F = ((V+Vr)/(V-Vs))*Fs = 480 Hz.
((343+0)/(343-Vs))*444 = 480
((343)/(343-Vs))*444 = 480
152292/(343-Vs) = 480
Cross multiply:
164640-480Vs = 152,292
-480Vs = 152,292-164,640 = -12,348
Vs = 25.725 m/s.

• physics -

F = Frequency as heard by receiver(man).
V = Velocity of sound in air.
Vr = Velocity of the receiver(man).
Vs = Velocity of source(car).
Fs = Frequency of source.

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