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A siren placed at a railway platform is ...

A siren placed at a railway platform is emitting sound of frequency `5 kHz`. A passenger sitting in a moving train `A` records a frequency of `5.5kHz` while the train approaches the siren. During his return journey in a different train `B` he records a frequency of `6.0 kHz` while approaching the same siren. the ratio the velocity of train `B` to that of train `A` is

A

`(242)/(252)`

B

`2`

C

`(5)/(6)`

D

`(11)/(6)`

Text Solution

Verified by Experts

The correct Answer is:
B
Using the formula `f' = f ((v+v_(0))/(v))`
we get, `5.5=5((v+v_(A))/(v))`...(i)
and `6.0=5((v+v_(B))/(v))`...(ii)
Here
v = speed of sound
`V_(A)` = speed of train
`V_(B)` = speed of train B
Solving equations (i) and (ii) `(V_(B))/(V_(A)) =2`
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ALLEN -WAVES AND OSCILLATIONS-Part-1(Exercise-05)[B]
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