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

Explanation:

use

$v = f \lambda$

$\frac{v_{1}}{f_1} = \frac{v_{2}}{f_2} \\ f_2 = 250 \times \frac{355}{345} \: hz = 257.24 \: hz$