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

Answer:

The speed of the police car is 33.98 m/s

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,

$\lambda = \frac{V}{F}\\\\\frac{V_1}{F_1} = \frac{V_2}{F_2}\\\\V_2 = \frac{V_1F_2}{F_1}\\\\V_2 = \frac{35*1330}{1370}\\\\V_2 = 33.98 \ m/s$

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