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A whistle revolves in a circle with an a...

A whistle revolves in a circle with an angular speed of `20 rad//sec` using a string of length `50 cm`. If the frequency of sound from the whistle is `385 Hz`, then what is the minimum frequency heard by an observer which is far away from the centre in the same plane? `v=340m//s`

A

`333 Hz`

B

`374 Hz`

C

`385 Hz`

D

`394 Hz`

Text Solution

Verified by Experts

The correct Answer is:
B

`v_(s) = R omega = 0.5 xx 20 = 10 m//s`
Minimum frequency will be heard when source is at `B`
`f_(min) = f((v)/(v+v_(s))) = 385((340)/(340+10))`
`= 374 Hz`
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