Speed ​​of sound

speed of sound in airplanes

Surely many times you have seen that when there is a storm the first thing that there is is a light that is the lightning and then the sound arrives. This is due to the Speed ​​of sound. Scientists have found what is the maximum speed that sound can propagate through the air. In physics this is quite important.

Therefore, we are going to dedicate this article to tell you everything you need to know about the speed of sound and how it propagates.

Speed ​​of sound

Speed ​​of sound

The speed of propagation of a sound wave depends on the characteristics of the medium in which it is propagated, not on the characteristics of the wave or the force that produces it. This speed of propagation of sound waves is also called the speed of sound.In the Earth's atmosphere, the temperature is 20ºC, which is 343 meters per second.

The speed of sound varies with the propagation medium and the way it propagates in the medium helps to better understand certain characteristics of the transmission medium. When the temperature of the propagation medium changes, the speed of sound will also change. This is because an increase in temperature leads to an increase in the frequency of interactions between particles that carry vibrations, which translates into an increase in the speed of the wave.

Generally speaking, the speed of sound in solids is higher than in liquids and the speed of sound in liquids is higher than in gases. This is because the more solid matter, the greater the degree of cohesion of the atomic bonds, which favors the propagation of sound waves.

The speed of sound propagation depends mainly on the elasticity of the medium that propagates it. Elasticity refers to the ability to restore its original shape.

What is sound

Sound is a pressure wave that can propagate through air by compression and depression. The sound that we perceive around us is nothing more than energy generated by vibrations that propagate through the air or any other medium, which can be received and heard when it reaches the human ear. We know that sound travels in the form of waves.

Waves are vibratory disturbances in the medium, which transfer energy from one point to another without direct contact between these two points. We can say that the wave is produced by the vibration of the particles of the medium through which it passes, that is, the propagation process corresponding to the longitudinal displacement (in the direction of propagation) of the air molecules. The area with large displacement appears in the area where the amplitude of the pressure change is zero and vice versa.

The sound in a speaker

speaker

Air in a tube with a speaker at one end and closed at the other end vibrates in the form of waves. Static longitudinally. Own modes of vibration of tubes with these characteristics. It corresponds to a sine wave, whose wavelength is such that there is a point of zero amplitude. The exhaust node at the end of the speaker and the closed end of the tube, because the air cannot move freely due to the speaker and the tube cap, respectively. In these nodes we have a maximum variation of the pressure, an antinode or belly, of the standing wave.

Speed ​​of sound in different media

sound experiment

The speed of sound varies according to the medium in which the sound wave propagates. It also changes with the temperature of the medium. This is because an increase in temperature causes an increase in the frequency of interactions between particles that carry vibrations, and an increase in this activity increases the speed.

For example, in snow, sound can travel long distances. This is due to refraction under snow, which is not a homogeneous medium. Each layer of snow has a different temperature. The deepest places that the sun cannot reach are colder than the surface. In these cooler layers close to the ground, the speed of sound propagation is slower.

Generally speaking, the speed of sound is greater in solids than in liquids and greater in liquids than in gases. This is because the higher the cohesion of the atomic or molecular bonds, the stronger the substance. The speed of sound in air (at a temperature of 20 ° C) is 343,2 m / s.

Let's see the speed of sound in some media:

  • In air, at 0 ° C, sound travels at a speed of 331 m / s (for every degree Celsius the temperature rises, the speed of sound increases by 0,6 m / s).
  • In water (at 25 ° C) it is 1593 m / s.
  • In tissues it is 1540 m / s.
  • In wood it is 3700 m / s.
  • In concrete it is 4000 m / s.
  • In steel it is 6100 m / s.
  • In aluminum it is 6400 m / s.
  • In cadmium it is 12400 m / s.

The propagation speed of the pressure wave is very important in the study of the resonance phenomenon in the collector of a reciprocating engine and depends on the characteristics of the environment. For example, for gases, the vaporized mixture in the intake manifold or the gases burned in the exhaust manifold depend on their density and pressure.

Types of propagating waves

There are two types of waves: longitudinal waves and transverse waves.

  • Longitudinal wave: Wave in which the particles of a medium vibrate from one side to the other in the same direction as the wave. The medium can be solid, liquid or gaseous. Therefore, sound waves are longitudinal waves.
  • Transverse wave: Wave in which the particles in the medium vibrate up and down "at right angles" to the direction of movement of the wave. These waves only appear in solids and liquids, not gases.

But remember that waves travel in all directions, so it's easier to think of them as passing through a sphere.

I hope that with this information you can learn more about the speed of sound and its characteristics.


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