Unless specifically stated otherwise, you may assume the speed of sound for all the scenarios below is 350 m/s.1. A police car is driving at 14 m/s towards a café. His siren is on blasting a frequency of 720 Hz. What frequency will people in the café hear as he approaches and what will they hear after he’s passed?

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LarkynN463463 LarkynN463463 · Answer 1 · 2022-10-25T22:45:05+02:00

ANSWER:

750 Hz and 692.3 Hz

STEP-BY-STEP EXPLANATION:

Given:

f0 = 720 Hz

vs = 14 m/s

vr = 0 m/s

v = 350 m/s

The corresponding formula for the Doppler effect is as follows:

[tex]f_s=f_o\left(\frac{v\pm\:v_o}{v\pm\:v_s}\right)[/tex]

The first scenario the police car is approaching the cafe, therefore:

[tex]\begin{gathered} f_s=720\cdot\left(\frac{350+0}{350-14}\right) \\ \\ f_s=750\text{ Hz} \end{gathered}[/tex]

The second scenario the police car is moving away from the cafe, therefore:

[tex]\begin{gathered} f_s=720\cdot\left(\frac{350+0}{350+14}\right) \\ \\ f_s=\:692.3\text{ Hz} \end{gathered}[/tex]

Therefore, the frequency that will be heard when approaching is 750 Hz and when passing the frequency would be 692.3 Hz.