# How fast is the sedan?

In the above diagram, an ambulance moving at a constant speed of $$20 \text{ m/s}$$ generates a sound of frequency $$1080 \text{ Hz}.$$ Calvin is chasing the ambulance in his sedan at a constant speed. If the frequency of the sound measured by Calvin from his car is $$1050 \text{ Hz},$$ then what is the speed of Calvin's sedan?

The speed of sound in the air is $$340 \text{ m/s}.$$

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