出典:Wikipedia
出典:『Wikipedia』 (2011/06/20 06:56 UTC 版)
Mach number (Ma or M) (generally
/ˈmɑːk/, sometimes /ˈmɑːx/ or /ˈmæk/) is the speed of an object moving through air, or any other fluid substance, divided by the speed of sound as it is in that substance for its particular physical conditions, including those of temperature and pressure. It is commonly used to represent the speed of an object when it is traveling close to or above the speed of sound.