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 1 models of the previous four years. The 302 Windsor returned in 1975, rated at and of torque, giving the Pinto platform a notable performance boost. Also available was a 4-speed manual. The Mach 1 remained mostly unchanged in 1976, as a new performance model - the Cobra II - was introduced alongside. 1977 proved to be the weakest sales year of the Mach 1 to date, selling only 6,719 units. The nameplate remained for one more year, upon when it was discontinued with the advent of the third generation Mustang in 1979. During the 1990s, the preeminent performance Mustang