How fast is the speed of mach one?
Mach is a term for velocity relative to the speed of sound where Mach one is the speed of sound. At sea level in air, mach 1 is 764 mph. At 10000 feet, that decreases to 664 mph. Sound travels faster in liquids ( almost 3300 mph in water) and faster still in metals (almost 11000 mph in steel.)
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