tHE SPEED OF SOUND IN AIR IS 1100 FEET PER SECOND. THE SPEED OF SOUND IN STEEL IS 1500 FEET PER SECOND. ROBIN ONE EAR PRESSED AGAINST THE RAILROAD TRACK, HEARS A SOUND THROUGH THE RAIL SIX SECONDS BEFORE HEARING THE SAME SOUND THROUGH THE AIR. TO THE NEAREST FOOT HOW FAR AWAY IS THE SOURCE OF THAT SOUND