A train is sounding its horn as it approaches a station. The engine driver hears a note of frequency f0 and of constant amplitude as the train slows down and stops next to a platform. A person standing at the end of the platform ahead of where the train stops also hears the sound produced by the horn. What happens to the amplitude and to the frequency of the sound heard by the person as the train slows down and stops?

Answer:

27) F

In this case, the source of sound is the train and the observer is the person. As the source moves closer to the observer, the amplitude increases due to the superimposition of waves.
The frequency would decrease as the train slows down and stops. Naturally, it would decrease to the frequency that the engine driver hears which is f