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A train, standin in a station yard, blow...

A train, standin 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 ini still air is `34om//s,

A

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

B

the speed of sound for the observer standing on the platform is 350m`//`s.

C

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

D

the frequency of sound as heard by the observer staing on the platform will decrease.

Text Solution

Verified by Experts

The correct Answer is:
A, B
Here, `v=400Hz, upsilon=340m//s, w=10m//s.`
(a) The frequency of sound as heard by an observer standing on platform `=400Hz` only, a sit is not affected by motion of wind alone.
(b) Speed of sound for observer standin on platform, `upsilon^(')+w=340+10=350m//s`
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