A whistle of frequency 540 Hz rotates in a horizontal circle of radius 2 m at an angular speed of `15(rad)/(s)`. What is the lowest and the highest frequency heard by a listener a long distance away at rest with respect to the centre of the circle? (Velocity of sound in air is `c=330(m)/(s)`.)

Explanation

In general
`n'=(c-v_0)/(c-v_S)xxn`
here `v_0=0` and `v_S=omegar=15xx2=30(m)/(s)`
When the source moves away from the observer, the apparent frequency in minimum and when it moves towards the observer, the apparent frequency in maximum
`n_(min)=(330)/(330-(-30))xx540=495Hz`
`n_(max)=(330)/(330-30)xx540=594Hz`.