Okay, so if Mach 5 is "3800 mph", how can Mach 10 be "about 7200 mph"?
31 - "Okay, so if Mach 5 is "3800 mph", how can Mach 10 be "about 7200 mph"?"
Mach is a measurment of the speed of sound, in the air. This varies with air density. Mach 1 is basically the speed of sound at sea level.
So linear distance speeds are not equivalent measures to mach speed.
At sea level, Mach 1 is 760 MPH. At 35,000 feet, Mach 1 is 660 MPH.