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At each of two stations A and B, a siren...

At each of two stations A and B, a siren is sounding with a constant frequency of 250 cycle `s^-1`. A cyclist from A proceeds straight towards B with a velocity of `12kmh^-1` and hear `5 beats//s`. The velocity of sound is nearly:

A

`328 ms^(-1)`

B

`320 ms^(-1)`

C

`333 ms^(-1)`

D

`336 ms^(-1)`

Text Solution

Verified by Experts

The correct Answer is:
C

If `f_(B)` is the frequency as heard by cyclist from source B and `f_(A)` is the frequency as heard by the cyclist form source A
Then `f_(B)-f_(A)=5`
`rArr 250((V_(s)+10/3)/(V_(s)))-250((V_(s)-10/3)/(V_(s)))=5`
`V_(s)=1000/3=333 m//s`
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