Speed of sound Totally Explained

Everything about Speed Of Sound totally explained

Sound is a vibration that travels through an elastic medium as a wave. The speed of sound describes how much distance such a wave travels in a certain amount of time. In dry air at 20 °C (68 °F), the speed of sound is 343 m/s (1235 km/h, or 770 mph, or 1129 ft/s).
To find the velocity of a sound wave in dry air at any temperature, use the formula: s = 331 + 0.6(T) where s represents the final speed, 331 is the speed of sound at 0°C in meters/second and T is the air temperature in centigrade. For example if the room temperature is 20°C, then the speed of sound will be s = 331 + 0.6(20), so the speed of sound would be 343 m/s. Although it's commonly used to refer specifically to air, the speed of sound can be measured in virtually any substance. Sound travels faster in liquids and non-porous solids than it does in air.

Basic concept

The transmission of sound can be explained using a toy model consisting of an array of balls interconnected by springs. For a real material the balls represent molecules and the springs represent the bonds between them. Sound passes through the model by compressing and expanding the springs, transmitting energy to neighboring balls, which transmit energy to their springs, and so on. The speed of sound through the model depends on the stiffness of the springs (stiffer springs transmit energy more quickly). Effects like dispersion and reflection can also be understood using this model.
In a real material, the stiffness of the springs is called the elastic modulus, and the mass corresponds to the density. All other things being equal, sound will travel more slowly in denser materials, and faster in stiffer ones. For instance, sound will travel faster in iron than uranium, and faster in hydrogen than nitrogen, due to the lower density of the first material of each set. At the same time, sound will travel faster in iron than hydrogen, because the internal bonds in a solid like iron are much stronger than the gaseous bonds between hydrogen molecules. In general, solids will have a higher speed of sound than liquids, and liquids will have a higher speed of sound than gases.
Some textbooks mistakenly state that the speed of sound increases with increasing density. This is usually illustrated by presenting data for three materials, such as air, water and steel. With only these three examples it indeed appears that speed is correlated to density, yet including only a few more examples would show this assumption to be incorrect. blah blah blah.

General formulas

In general, the speed of sound c is given by ť

c = sqrt

In contrast to a gas, the pressure and the density are provided by separate species, the pressure by the electrons and the density by the ions. The two are coupled through a fluctuating electric field.

Gradients

When sound spreads out evenly in all directions, the intensity drops in proportion to the inverse square of the distance. However, in the ocean there's a layer called the 'deep sound channel' or SOFAR channel which can confine sound waves at a particular depth, allowing them to travel much further. In the SOFAR channel, the speed of sound is lower than that in the layers above and below. Just as light waves will refract towards a region of higher index, sound waves will refract towards a region where their speed is reduced. The result is that sound gets confined in the layer, much the way light can be confined in a sheet of glass or optical fiber.
A similar effect occurs in the atmosphere. Project Mogul successfully used this effect to detect a nuclear explosion at a considerable distance.

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