Mach number which was also unit-first, and may have influenced the use of the term Mach. In the decade preceding faster-than-sound human flight, aeronautical engineers referred to the speed of sound as "Mach's number", never "Mach 1". Mach number is useful because the fluid behaves in a similar manner at a given Mach number, regardless of other variables. As modeled in the International Standard Atmosphere, dry air at mean sea level, standard temperature of , the speed of sound is . The speed of sound is not a constant; in a gas, it increases as the absolute temperature increases, and since atmospheric
Mach Five car appeared to have the same functions as the Mach Five in the original series, but the buttons Speed pressed to activate them seemed more or less random, with the same button activating different abilities (or different buttons activating the same ability) in different episodes. In 2000, a prototype Mach Five with actual cutting blades was produced as a concept car. 100 production models were planned to be made in 2002 as a street legal vehicle. Built on a 2001 Chevrolet Corvette Chassis, the body was to be extensively modified to look like the Mach Five. It was to have