Question

A police car travels towards a stationary
observer at a speed of 15 m/s. The siren
on the car emits a sound of frequency 250
Hz. Calculate the recorded frequency.
The speed of sound is 340 m/s.​

Answer 1

The recorded frequency = 261.53Hz

Let f' be the recorded frequency

f = frequency of sound emitted by the siren on the police car = 250Hz

v' = speed of police car = 15 m/s

v = speed of sound in the air = 340 m/s

Using Doppler's effect to find the frequency recorded by the listener -

recorded frequency = frequency × (velocity of listener / velocity of source)

f' = f ( v/(v-v'))

=> f' = 250×(340/325)

=> f' = 262.53 Hz

The recorded frequency = 261.53Hz

Answer 2

Explanation:

i hope this helps you guys...