Mach number temperature generally decreases with increasing altitude between sea level and , the speed of sound also decreases. For example, the standard atmosphere model lapses temperature to at altitude, with a corresponding speed of sound (Mach1) of , 86.7% of the sea level value. While the terms "subsonic" and "supersonic", in the purest sense, refer to speeds below and above the local speed of sound respectively, aerodynamicists often use the same terms to talk about particular ranges of Mach values. This occurs because of the presence of a "transonic regime" around M = 1 where approximations of the Navier-Stokes equations used
Mach Rider and obstacles on the road. The up and down buttons are used to shift gears. Mach Rider's bike has four speeds and shifting to the fourth gear at high speed will grant the player in instant speed boost. Conversely, the player remaining in a higher gear while stopping results in a slower acceleration. In each round, points can be scored by destroying enemies and certain obstacles with the machine gun. The number of points scored for destroying enemies and obstacles is determined by the type of enemy or obstacle destroyed. If the player blocks an attacking enemy by ramming it