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 of his father's motor company). In the 1993 American remake, the design was completely changed. Its name probably derives from the fact that speeds above Mach 5 are known as hypersonic. However, the Mach Five cannot reach Mach speeds. The name is also a pun in two languages: the word for "five" in Japanese is "go". However, the "go" used for the car's name is a suffix attached to the names of ships, etc. Thus, the car is known in the Japanese version as simply the "Mach". Actual race cars that closely resemble the Mach Five are the 1966 Japanese