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J. Perelman
"Entertaining physics". Book 2.
Chapter 10. Sound. Wave motion

SOUND AND RADIO WAVES

Sound travels about a million times slower than light; and as the speed of radio waves coincides with the velocity of propagation of light vibrations, the sound is a million times slower signal. Hence a curious consequence, the essence of which it turns out the problem: who will hear the first chord of the pianist, the visitor concert hall, sitting 10 metres from the piano, or the listener of the apparatus, the receiving game pianist in his apartment, 100 kilometers from the audience?

Oddly enough, the listener will hear the chord before the visitor concert hall, although the first sitting 10,000 times farther from the musical instrument. In fact: radio waves run through a 100-kilometer distance in

100 / 300 000= 1 / 3 000 seconds

The sound passes the 10 m distance in

10 / 340 = 1 / 34 seconds.

This shows that the transmission of sound radio will require almost a hundred times less time than the transmission of sound through the air.

Entertaining physics J. Perelman

 




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