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I need some help w/ this:


A police car siren emits a frequency of 2010 Hz when stationary. When it is driving toward a stationary car, the other driver hears a frequency of 2120 Hz. How fast is the police car driving?


Using the doppler's effect equation, I got the answer ±16.3, but that apparently isn't the correct answer.

Edited: Ohhh Ok, I got it, answer is 17.7 ... whoops

Respuesta :

Answer:

The velocity of the police car is, v = 17.798 m/s

Explanation:

Given data,

The actual frequency of the siren, f = 2010 Hz

The observed frequency of siren is, f' = 2120 Hz

The velocity of the observer, v' = 0 m/s

The velocity of the source, v = ?

The formula for Doppler effect,

                            [tex]f'=\frac{(V+v')}{(V-v)}f[/tex]

Where,

                         V - velocity of sound waves in air.

                          [tex]v=V-(V+v')\frac{f}{f'}[/tex]

Substituting the given values,

                         [tex]v=343-(343+0)\frac{2010}{2120}[/tex]

                                 v = 17.798 m/s

Hence, the velocity of the police car is, v = 17.798 m/s

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