A driver travels northbound on a highway at a speed of 240 m

A driver travels northbound on a highway at a speed of 24.0 m/s. A police car, traveling southbound at a speed of 34.0 m/s, approaches with its siren producing sound at a frequency of 2450 Hz.

(a) What frequency does the driver observe as the police car approaches? Hz

(b) What frequency does the driver detect after the police car passes him? Hz

(c) Repeat parts (a) and (b) for the case when the police car is traveling northbound.

while police car overtakes Hz

after police car passes Hz

Solution

fro Doppler Effect

a)f\'=f(v+v0)/(v-vs) (while approaches)

f\' = 2450*(343+24)/(343-34)

f\' = 2909.87 Hz

b.

f\'=f(v - v0)/(v+ vs)

f\'= 2450(343-24)/(343+34)

f\' =2073.076 Hz

when source is in motion

c)

f\'= 2450 * (343-24)/(343-34)

f\' = 2529.28 Hz

f\'=2550*(343+20)/(343+45)

f\' =2385.7 Hz