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A train is passing by a platform at a co...

A train is passing by a platform at a constant speed of `40m//s`. The train horn is sounded at a frequency of `378 Hz`. Find the overall change in frequency as detected by a person standing on the platform, as the train moves from approaching to receding. (Take velocity of sound in air as `320m//s`).

A

`104Hz`

B

`92Hz`

C

`84Hz`

D

`96Hz`

Text Solution

Verified by Experts

The correct Answer is:
D

For situation 1, `f_(ap1)=(v-0)/(v-v_S)xxf`
`=(320)/(320-40)xx378=432Hz`
For situation 2, `f_(ap2)=(v)/(v-(-V_S))xxf=336Hz`
`f=f_(ap1)-f_(ap2)=96Hz`
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