Question

85. A train whistling at constant frequency is
moving towards a station at a constant
speed v. The train goes past a stationary
observer on the station. The frequency n
of the sound as heard by the observer is
plotted as a function of time t(figure).
Identify the expected curve.​

Answer 1

Answer:

Whistling train is the source of sound, υs=B. Before crossing a stationary observer on station, frequency heard is n′=υn(υ-υs)=υnυ-V= constant, and n′>n.

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