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A train moves towards a stationary obser...

A train moves towards a stationary observer with speed `34 m//s`. The train sounds a whistle and its frequency registered by the observer is `f_(1)`. If the train's speed is reduced to `17 m//s`, the frequency registered is `f_(2)`. If the speed of sound of `340 m//s`, then the ratio `f_(1)//f_(2)`is

A

18/19

B

`1//2`

C

2

D

19/18

Text Solution

Verified by Experts

The correct Answer is:
D
`n_1=n_0(340)/(340-34)=10/9n_0`
`n_2=n_0(340)/(340-17)=20/19n_0`
`(n_1)/(n_2)=10/9xx19/20=19/18`
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