Mach number which was also unit-first, and may have influenced the use of the term Mach. In the decade preceding faster-than-sound human flight, aeronautical engineers referred to the speed of sound as "Mach's number", never "Mach 1". Mach number is useful because the fluid behaves in a similar manner at a given Mach number, regardless of other variables. As modeled in the International Standard Atmosphere, dry air at mean sea level, standard temperature of , the speed of sound is . The speed of sound is not a constant; in a gas, it increases as the absolute temperature increases, and since atmospheric
Mach 2 (film) Mach 2 (film) Mach 2 is a 2001 American direct-to-video action disaster thriller film directed by Fred Olen Ray. It was the first film to feature the airliner Concorde being hijacked. U.S. Senator Stuart Davis, running against the Vice-President, plans a trip to the Balkans to negotiate the release of American servicemen being held hostage by terrorists. Before he leaves, he receives a disk documenting evidence that the Vice-President has been trying to revive the American economy by causing a war in the Balkans. He announces his plans at Washington Dulles International Airport to show it to both sides in