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 Rider on it. When the car is placed inside of it, it can be charged up and let loose at high speed. Later, "Mach Rider" was released as part of the "Nintendo Vs. Series" arcade variations. It was essentially a modified version of the Endurance Course from the original game. Each time the player completed a level, a bit more of an image was gradually revealed of a woman with a dagger appears next to Mach Rider's bike. While "Mach Rider" has not gained a true sequel, many elements from the game, such as the futuristic setting, incredible high speeds and