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f' = Frequency Perceived (by Truck Driver) f0 = Natural Frequency v = Speed of Sound vs = Speed of Source (Police Car) vd = Speed of Detector (Truck Driver) f' before = f0 * [ (v-vd) / (v-vs) ] = 800Hz [ (340-17 m/s) / (340-41m/s) ] = 864.21 Hz f' after =...