# Speed Of Sound

## Speed Of Sound

The speed of sound is the distance travelled during a unit of time by a sound wave propagating through an elastic medium. In dry air at 20 °C (68 °F), the speed of sound is 343.2 metres per second (1,126 ft/s). This is 1,236 kilometres per hour (768 mph), or about one kilometer in three seconds or approximately one mile in five seconds.

In fluid dynamics, the speed of sound in a fluid medium (gas or liquid) is used as a relative measure of speed itself. The speed of an object (in distance per time) divided by the speed of sound in the fluid is called the Mach number. Objects moving at speeds greater than Mach1 are traveling at supersonic speeds.

### Speed Of Sound   Speed Of Sound Speed Of Sound  Speed Of Sound     The speed of Sounds is the distance travelled during a unit of time by a Sounds wave propagating through an elastic medium. In dry air at sea level (101.325 kPa) and 20 °C (68 °F), the speed of Sounds is 343.2 metres per second (1,126 ft/s). This is 1,236 kilometres per hour (768 mph), or about one kilometer in three seconds or approximately one mile in five seconds.

In fluid dynamics, the speed of Sounds in a fluid medium (gas or liquid) is used as a relative measure of speed itself. The speed of an object divided by the speed of Sounds in the fluid is called the Mach number. Objects moving at speeds greater than Mach1 are traveling at supersonic speeds.

The speed of Sounds in an ideal gas is independent of frequency, but does vary slightly with frequency in a real gas. It is proportional to the square root of the absolute temperature, but is independent of pressure or density for a given ideal gas. Sounds speed in air varies slightly with pressure only because air is not quite an ideal gas. In addition, for different gases, the speed of Sounds is inversely proportional to the mean molecular weight of the gas, and is affected to a lesser extent by the number of ways in which the molecules of the gas can store heat from compression, since Sounds in gases is a compression wave. Although (in the case of gases only) the speed of Sounds is expressed in terms of a ratio of both density and pressure, these quantities cancel in ideal gases at any given temperature, composition, and heat capacity. This leads to a velocity formula for ideal gases which includes only the latter independent variables.

In common everyday speech, speed of Sounds refers to the speed of Sounds waves in air. However, the speed of Sounds varies from substance to substance. Sounds travels faster in liquids and non-porous solids than it does in air. It travels about 4.3 times as fast in water (1,484 m/s), and nearly 15 times as fast in iron (5,120 m/s), than in air at 20 degrees Celsius. Sounds waves in solids are composed of compression waves (just as in gases and liquids), but there is also a different type of Sounds wave called a shear wave, which occurs only in solids. These different types of waves in solids usually travel at different speeds, as exhibited in seismology. The speed of a compression Sounds wave in solids is determined by the medium’s compressibility, shear modulus and density. The speed of shear waves is determined only by the solid material’s shear modulus and density.