Question

riving you along a highway at 35.0 m/s when you hear the siren of a police car approaching you from behind and you perceive the frequency as 1370 Hz. You are relieved that he is in pursuit of a different speeder when he continues past you, but now you perceive the frequency as 1330 Hz. What is the speed of the police car

Answer 1

The speed of the police car is 33.98 m/s

Step-by-step explanation:

Given;

first speed, v₁ = 35 m/s

first frequency, f₁ = 1370 Hz

second frequency, f₂ = 1330 Hz

second speed, v₂ = ?

Speed of sound is directly proportional to its frequency;

v = fλ

assuming the λ is constant, then,

`\lambda = (V)/(F)\\\\(V_1)/(F_1) = (V_2)/(F_2)\\\\V_2 = (V_1F_2)/(F_1)\\\\V_2 = (35*1330)/(1370)\\\\V_2 = 33.98 \ m/s`

Therefore, the speed of the police car is 33.98 m/s