Question

.A cop car's siren has a frequency of 700 Hz, if you are standing on the sidewalk as the cop car approaches you at a speed of 15 m/sec, what frequency would you hear? 20 °C

Answer 1

732 Hz

Step-by-step explanation:

Given the following :

Frequency (fs) of siren = 700Hz

Speed (vs) of approaching car = - 15m/sec

Velocity of listener(vl) = 0

Velocity of sound wave = 340m/s

From doppler effect, use the formula :

fl = [(v + vl) / (v + vs)] fs

Where fl is the frequency heard by the listener

fl = [(340 + 0) / (340 +(- 15) )] * 700

fl = [ 340 / 325] * 700

fl = 1.0461538 * 700

fl = 732.30769

fl = 732 Hz ( to the nearest whole number)