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A railroad train is travelling at 30(m)/...

A railroad train is travelling at `30(m)/(s)` in still air. The frequency of the note emitted by locomotive whistle is 500 Hz. Speed of sound is `345(m)/(s)`.
Q. What is the frequency of the sound waves heard by a stationary listener in front of the train?

A

`547.6Hz`

B

`690.6Hz`

C

`590.9Hz`

D

`520.3Hz`

Text Solution

Verified by Experts

The correct Answer is:
A

In front of train: velocity of observer is `V_0=0(m)/(s)` Velocity of source is `V_0=+30(m)/(s)`. The direction from S to O is considered to be the positive direction.
Hence, the apparent frequency is
`f'=f((c-V_0)/(c-V_S))=f((c-0)/(c-30))`
`impliesf'=(500xx345)/(345-30)=547.62Hz`
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