When a tuning fork is vibrated in air, sound waves travel from the fork and frequency observed, by the observer is same as that of the source. But if source or/and observer are moving relative to the medium then the frequency will change. If the source is moving towards the observer, observer will receive higher frequency as compare with emitted by source

Here source of sound moving along the X-axis at a speed of 22 m/s continuously emitting a sound of frequency 2.0 KHz which travels in air at a speed of 330 m/s. A listener Q stands on the Y axis at a distance of 330 m from the origin. At t = 0, the source crosses the origin P.

(i) After what time does the sound emitted from the source at P reach the listener Q.