A boy standing near a railway track places his ear against the steel rail and hears the sound of an…

A boy standing near a railway track places his ear against the steel rail and hears the sound of an approaching train before he hears it through the air. Why does this happen?
  1. Sound travels faster in steel than in air
  2. Steel rails produce sound automatically
  3. Air slows down sound waves using friction
  4. Sound waves travel only along metal objects

Solution

The speed of sound in solid steel is around $5000\text{ m/s}$, which is much faster than its speed in air (about $340\text{ m/s}$).

Asked in: Homi Bhabha Practice

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