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 345 horsepower, and cost between $75,000 and $125,000 each. The Petersen Automotive Museum in Los Angeles, California has a mid-engine prototype of the Mach Fives in its collection. The Mach Five appears in the live-action film adaptation "Speed Racer", directed by the Wachowski brothers, produced by Joel Silver, and released by Warner Bros. Pictures. The Mach Five is an actual vehicle and used in the major race of the film. Instead of being driven on pavement, it was hung from a crane and had its effects computer-generated. Along with the Mach Five, the movie features the "Mach 4" and the