A train moves towards a stationary observer with speed 34 m s - 1 . The train sounds a whistle and its frequency registered by the observer is v 1 . If the train's speed is reduced to 17 m s - 1

Question

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

TestHub · Accepted Answer

Perceived frequency by observer in Ist case

$v_{1} = v (\frac{v}{v - v_{s}})$

$∴ v_{1} = v (\frac{340}{340 - 34}) = \frac{340 v}{306}$

Perceived frequency by observer in IInd case

$v_{2} = v (\frac{340}{340 - 17}) = \frac{340 v}{323}$

Therefore,

$\frac{v_{1}}{v_{2}} = \frac{340 v}{306} \times \frac{323}{340 v} = \frac{323}{306} = \frac{19}{18}$

Physics - Sound Wave Question with Solution | TestHub

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