TITLE: The travel of soundwaves
QUESTION [2 upvotes]: As we are waiting in the subway station, we will hear the rail screeching when the train is arriving. Is it because soundwaves travels faster in a solid substance than in air? or is it a compartment in the rail?

REPLY [1 votes]: You don't hear it throught the rails unless you put your ear to the rails and you shouldn't do that. What you hear is the sound propagating through the air. The fact that you hear it before the train arrives is due to the fact that the speed of sound is larger than the speed of the train. The fact that the speed of sound in the solid rail is larger than in air is secondary to this problem.
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