A train approaching a platform at a speed of 54 km/h sounds a whistle. An observer on the platform finds its frequency to be 1620 Hz. The train passes the platform keeping the whistle on and without slowing down. What frequency will the observer hear after the train has crossed the platform? The speed of sound in air = 332 m/s.

The speed of the train is 54 Km/h =15ms-1


f= 1620 Hz


v= 332 ms-1


When the train approaches the station,





When the train leaves the station,





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