A car speeding down the highway honks its horn, which has a frequency 392 Hz, but a resting bystander hears the frequency 440 Hz. If the spe

Question

A car speeding down the highway honks its horn, which has a frequency 392 Hz, but a resting bystander hears the frequency 440 Hz. If the speed of sound in air is 343 m/s, how fast is the car moving

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Ngọc Diệp 2 months 2021-09-02T15:22:44+00:00 1 Answers 0 views 0

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    2021-09-02T15:24:04+00:00

    Answer:

    37.42 m/s

    Explanation:

    We know that apparent frequency, \bar f is given by

    \bar f=f\frac {V}{V-V_s} where f is the given frequency in this case 392, V is the speed of sound in air which is given as 343 and V_s is the speed of car which is unknown, \bar f is given as 440 Hz

    440=392\times \frac {343}{343-V_s}\\343-V_s=392\times \frac {343}{440}=305.5818182\\V_s=343-305.5818182=37.41818182\approx 37.42 m/s

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