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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.
Mach number. 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 Czech physicist and philosopher Ernst Mach . where: M is the local Mach number, u is the local ...
The voiced speech of a typical adult male will have a fundamental frequency from 90 to 155 Hz, and that of a typical adult female from 165 to 255 Hz. [3] Thus, the fundamental frequency of most speech falls below the bottom of the voice frequency band as defined. However, enough of the harmonic series will be present for the missing fundamental ...
The speed of light in vacuum, commonly denoted c, is a universal physical constant that is exactly equal to 299,792,458 metres per second (approximately 300,000 kilometres per second; 186,000 miles per second; 671 million miles per hour). [Note 3] According to the special theory of relativity, c is the upper limit for the speed at which ...
The speed of sound in any chemical element in the fluid phase has one temperature-dependent value. In the solid phase, different types of sound wave may be propagated, each with its own speed: among these types of wave are longitudinal (as in fluids), transversal, and (along a surface or plate) extensional. [1]
If relativistic effects are important, the speed of sound is calculated from the relativistic Euler equations. In fresh water the speed of sound is approximately 1,482 m/s (5,335 km/h; 3,315 mph). In steel, the speed of sound is about 5,960 m/s (21,460 km/h; 13,330 mph).
A sound speed profile shows the speed of sound in water at different vertical levels. It has two general representations: tabular form, with pairs of columns corresponding to ocean depth and the speed of sound at that depth, respectively. a plot of the speed of sound in the ocean as a function of depth, where the vertical axis corresponds to ...
In aerodynamics, the critical Mach number ( Mcr or M*) of an aircraft is the lowest Mach number at which the airflow over some point of the aircraft reaches the speed of sound, but does not exceed it. [1] At the lower critical Mach number, airflow around the entire aircraft is subsonic. Supersonic aircraft such as the Concorde and combat ...