Physics doppler effect
posted by Joan on .
A person standing close to a railroad crossing hears the whistle of an approaching train. He notes that the pitch of the whistle drops as the train passes by and moves away from the crossing. The frequency of the approaching whistle is 523 Hz, and drops to 491 Hz after the train is well past the crossing. What is the speed of the train? Use 340 m/s for the speed of sound in air. show work.

F = ((V+Vr) / (V+Vs))*Fo = 491.
((340+0) / (340+Vs)))*523 = 491,
177820 / (340+Vs) = 491,
166,940 + 491Vs = 177,820,
Vs = 22.2m/s = Speed of train. 
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