Question

A train whistle is 580 Hz when stationary. It is coming toward you at 18.8 m/s. What frequency do you hear?

(Speed of sound = 343 m/s) (Unit=Hz)

Answer 1

612 hz

Explanation:

580 + (580 / 343) * 18.8

= 612 Hz.

Answer 2

612 Hz.

Explanation:

The frequency of the sound will be proportionally higher when coming towards you. The increase is related to the speed of the train.

So the frequency will be:

580 + (580 / 343) * 18.8

= 612 Hz.

This is called the Doppler effect.