A whistle emmitting a sound of frequency `440 Hz` is tied to a string of `1.5m` length and rotated with an angular velocity of `20rad s^(-1) in the horizontal plane. Calculate the range of frequencies heard by an observer stationed at a large distance from the whistle.

Answer

C, D

Explanation

The whistle which is emmtting sound is being rotated in a circle.

`r = 1.5m`(given), `0mega = 20 rads^(-1)` (given)
We know that
When the source is instantaneously at the positon `A`, then the frequency heard by the observer will be
`v' = v[(v)/(v - v_(s))] = 440[((330)/(330 - 30)] = 484 Hz`
When the source is instantaneously at the positon `B`, then the frequency heard by the observer will be
`v" = v[(v)/(v + v_(s))] = 440[((330)/(330 + 30)] = 403.3 Hz`
Hence the ramge of frequency heard by the obsrever is `403.3 Hz` to `484 Hz.