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The frequency of the whistle of a train ...

The frequency of the whistle of a train is observed to drop from 280 Hz to 260 Hz as the train moves away from a stationary listerner on the platform. Calculate the speed of the train, if speed of sound in air is 340 m/s.

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The correct Answer is:
26.15 m/s
`v.=((v)/(v+v_s))v`
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