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Doppler Effect?
The siren on a police car produces a frequency of 225 Hz when it is stationary. When a person on the side of the road who is not moving, hears the siren as the police car approaches at 30 m/s what frequency do they hear?
(the speed of sound in this instance is 344 m/s)
1 Answer
- a simple manLv 61 decade agoFavorite Answer
The apparent frequency of the the siren is multiple of the true frequency and the ratio of the approaching speed of the sound waves and the ambient speed of sound.
Fa = Ft x (V(a) + V(s))/ V(s)
Fa(apparent) = 225 Hz x (30 + 344) /344 = 255 Hz x 374/344