Question

A motorcyclist is moving 24.5 m/s towards a stationary siren, and hears a 894 Hz sound. What is the frequency of the siren when the cyclist is stationary?

A motorcyclist is moving 24.5 m/s toward a stationary siren, and hears an 894 Hz sound. What is the frequency of the siren when the cyclist is stationary? (Hint: 894 Hz is the Doppler-shifted frequency.) (Speed of sound 343 m/s) (Unit Hz) nter

Answer 1

We know that the doppler frequency is given by
$f = f_{o}\left ( \frac{V+V_{o}}{V} \right )$
Where V is velocity of sound = 343 m/s
V_o is velocity of observer = 24.5 m/s
f_o is the original frequency
f is the doppler frequency = 894 Hz
Putting all the values
$894= f_{o}\left ( \frac{343+24.5}{343} \right )$
f_o = 792.4 Hz

Answer 2

830.14

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