Mach number Mach number In fluid dynamics, the Mach number (M or Ma) (; ) is a dimensionless quantity representing the ratio of flow velocity past a boundary to the local speed of sound. where: By definition, at Mach1, the local flow velocity is equal to the speed of sound. At Mach0.65, is 65% of the speed of sound (subsonic), and, at Mach1.35, is 35% faster than the speed of sound (supersonic). The local speed of sound, and thereby the Mach number, depends on the condition of the surrounding medium, in particular the temperature. The Mach number is primarily used to determine
Mach-O Mach-O Mach-O, short for Mach object file format, is a file format for executables, object code, shared libraries, dynamically-loaded code, and core dumps. A replacement for the a.out format, Mach-O offers more extensibility and faster access to information in the symbol table. Mach-O is used by most systems based on the Mach kernel. NeXTSTEP, macOS, and iOS are examples of systems that use this format for native executables, libraries and object code. Each Mach-O file is made up of one Mach-O header, followed by a series of load commands, followed by one or more segments, each of which contains between