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
Ford Mustang Mach 1 5800 rpm (4-speed automatic)." While on paper the 305 hp (228 kW) ratings seem a loss when compared to the 1999 and 2001 SVT Cobras which produced 320 hp (239 kW), in practice the Mach 1 engine produced similar peak horsepower and substantially more torque. Further differences included the use of Ford's solid rear axle with a 3.55 final ratio (As opposed to SVT's Independent Rear Suspension) also the availability of a 4 speed automatic in addition to the Tremec sourced 5 speed manual. Factory steel "Box" cross section subframe connectors were also added to increase chassis strength for both