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The Mach number (M or Ma), often only Mach, (/ mɑːk /; German: [max]) is a dimensionless quantity in fluid dynamics representing the ratio of flow velocity past a boundary to the local speed of sound. [1][2] It is named after the Austrian physicist and philosopher Ernst Mach. where: M is the local Mach number, u is the local flow velocity ...
Supersonic speed is the speed of an object that exceeds the speed of sound (Mach 1). For objects traveling in dry air of a temperature of 20 °C (68 °F) at sea level, this speed is approximately 343.2 m/s (1,126 ft/s; 768 mph; 667.1 kn; 1,236 km/h). Speeds greater than five times the speed of sound (Mach 5) are often referred to as hypersonic.
e. The speed of sound is the distance travelled per unit of time by a sound wave as it propagates through an elastic medium. More simply, the speed of sound is how fast vibrations travel. At 20 °C (68 °F), the speed of sound in air is about 343 m/s (1,125 ft/s; 1,235 km/h; 767 mph; 667 kn), or 1 km in 2.91 s or one mile in 4.69 s.
Hypersonic speed. "Hypersonic" redirects here. For other uses, see Hypersonic (disambiguation). In aerodynamics, a hypersonic speed is one that exceeds five times the speed of sound, often stated as starting at speeds of Mach 5 and above. [1] The precise Mach number at which a craft can be said to be flying at hypersonic speed varies, since ...
Ernst Waldfried Josef Wenzel Mach (/ mɑːx / MAHKH; German: [ɛʁnst ˈmax]; 18 February 1838 – 19 February 1916) was an Austrian physicist and philosopher, who contributed to the physics of shock waves. The ratio of the speed of a flow or object to that of sound is named the Mach number in his honour. As a philosopher of science, he was a ...
Therefore, for a boom to reach the ground, the aircraft's speed relative to the ground must be greater than the speed of sound at the ground. For example, the speed of sound at 30,000 feet (9,100 m) is about 670 miles per hour (1,080 km/h), but an aircraft must travel at least 750 miles per hour (1,210 km/h) (Mach 1.12) for a boom to be heard ...
Mach's principle. In theoretical physics, particularly in discussions of gravitation theories, Mach's principle (or Mach's conjecture[1]) is the name given by Albert Einstein to an imprecise hypothesis often credited to the physicist and philosopher Ernst Mach. The hypothesis attempted to explain how rotating objects, such as gyroscopes and ...
The sound source has now broken through the sound speed barrier, and is traveling at 1.4 times the speed of sound, c (Mach 1.4). Because the source is moving faster than the sound waves it creates, it actually leads the advancing wavefront. The sound source will pass by a stationary observer before the observer actually hears the sound it creates.