# Calculating the speed of an approaching vehicle given the frequency of a car horn

A student in a parked car honks the horn, which has a `proper' frequency of 300 Hz. An observer in an approaching vehicle measures the frequency of the sound to be 329 Hz. Calculate the speed of the approaching vehicle. Use 343 m/s as the speed of sound in air.

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#### Solution Preview

This is a problem related to the Doppler Effect.

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<br>The relevant formula is

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<br>fprime = f * (v +/- deltav) / v

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<br>where fprime = apparent freq. (Hz)

<br> f = true ...

#### Solution Summary

A problem related to the Doppler Effect is demonstrated.

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