Mach number is the ratio of speed to sound speed. The speed of sound (that is, the speed of sound propagation) has different values at different altitudes, temperatures and atmospheric densities, and it is only a relative value. The specific speed of each horse is not fixed. Mach is actually the name of Austrian physicist ernst mach (ernst mach, 1838- 19 16), and it is named after him, because this is the first time he has quoted this unit.

Ernst mach:

Mach was named in memory of Austrian scholar ernst mach (ernst mach, 1838- 19 16).

Mach (ernst mach,1838-02-18-16-02-19) is an Austrian-Czech physicist, psychologist, philosopher and founder of Mahism. 1838 February 18 was born in Moravia (now Czech Republic) and died in Hal near Munich, Germany.

Mach devoted his whole life to the research of experimental physics and published more than 100 research papers and reports. Mach's work of studying flying projectiles by schlieren technique is the most famous. His most important achievement is that he discovered the shock wave while studying the high-speed movement of objects in gas, and took clear photos of the shock wave.

In several papers from 65438 to 0887, he pointed out that an object moving in the air emits a spherical disturbance wave propagating at the speed of sound C. When the speed of the object v is greater than c, the wavefront of the disturbance wave forms a conical envelope surface with the object as the vertex (see Mach cone), and the relationship between the angle α formed by the conical generatrix and the moving direction of the object and V and C is sin α = c/v.

Reference to the above content: Baidu Encyclopedia-Mach