n :  a usu. high speed expressed by a Mach number <an airplane flying at 2> 
 
Mach, Ernst (1838-1916), Austrian physicist and philosopher. Mach established the basic principles of scientific positivism. In the 1870s he made classic studies on the perception of bodily rotation. Mach was also a pioneer in the study of supersonic projectiles and jets. In 1887 he described in a paper on projectiles in flight the angle between the axis of the projectile and the envelope of the waves produced. This angle forms the basis for the Mach number.
 
 
 
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