Question

A police car traveling at a speed of 30.0 meters per second sounds its siren, which has a frequency of 1.00 × 103 hertz. As the police car moves from a stationary pedestrian, the pedestrian detects a siren frequency of A.1.00 x 103 HzB.9.19 x 102 HzC.1.10 x 103 HzD.30.0 Hz

Answer 1

f = f source = ( speed air / speed air + speed source )

Where:

f = listener frequency (pedestrian)

speed of air = 340 m/s

speed of source (police car ) = 30 m/s

f souce = frequency of police car = 1 x 10^3 hz

f= 1 x 10^3 (340 / 340+30)

f= 919 hz = 9.19 x 10^2 hz