Ernst Mach of experimental physics concentrated on the interference, diffraction, polarization and refraction of light in different media under external influences. From there followed important explorations in the field of supersonic fluid mechanics. Mach and physicist-photographer Peter Salcher presented their paper on this subject in 1887; it correctly describes the sound effects observed during the supersonic motion of a projectile. They deduced and experimentally confirmed the existence of a shock wave of conical shape, with the projectile at the apex. The ratio of the speed of a fluid to the local speed of sound "v"/"v" is now called the Mach number. It
Ford Mustang Mach 1 (for use with 4-venturi carbs) versions. The 351C 4V (M code) engine featured 11.0:1 compression and produced at 5400 rpm. This new performance engine incorporated elements learned from the Ford 385 series engine and the Boss 302, particularly the poly-angle combustion chambers with canted valves and the thin-wall casting technology. For 1971, Ford reduced the content of the Mach 1. The standard features of the model were as follows: In 1971, the Mach 1 was available with three 351 Cleveland engines; the H-code 2-V, the M-code 4-V and beginning in May of 1971, the 351CJ (Cobra Jet or GT engine).