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A train, standing in a station yard, blo...

A train, standing in a station yard, blows a whistle of frequency 400Hz in still air. The wind starts blowing in the direction from the yard to the station with a speed of 10m//s. Given that the speed sound in still air is `340m//s`,

A

The frequency of sound as heard by an observer standing on the platform is 400 Hz.

B

The speed of sound for the observer standing on the platform is 330 `m s^(-1)`

C

The frequency of sound as heard by the observer standing on the platform will increase.

D

The frequency of sound as heard by the observer standing

Text Solution

Verified by Experts

The correct Answer is:
A
Here, `upsilon_(0)=400Hz, v=340ms^(-1),v_(w)=10ms^(-1)`
As there is no relative motion between the source and observer, therefore the frequency of sound remains unchanged.
Hence, the frequency of sound as heard by an observer standing on the platform is `upsilon_(0)= 400 Hz.`
As the wind is blowing in the direction of sound, therefore, for an observer standing on platform,
Speed of sound=`v+v_(w)=340+10=350ms^(-1)`
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