For many, even years after graduation is unknown what is actually the speed of sound in air.Someone casually listened to the teacher, while others simply do not fully understand the stated material.Well, maybe it's time to fill this gap in knowledge.Today, we do not just point out "dry" numbers, and explain the mechanism that determines the speed of sound in air.
As is known, air is a combination of different gases.Slightly more than 78% nitrogen accounted for almost 21% takes the oxygen, the remaining part is represented by carbon and inert gases.Consequently, it will be the speed of sound in the gaseous medium.
First, let's define what a sound.I'm sure many have heard the saying "sound waves" or "sound vibrations".Indeed, for example, reproducing cone speakers with a certain frequency range, which is classified as a human hearing system sounds.One of the laws of physics states that pressure in gases and liquids extends unchanged in all directions.It follows that under ideal conditions, the velocity of sound in the gas is uniform.Of course, in reality it holds its natural decay.We need to remember this feature, since it is this explains why the rate may vary.But we digress a bit from the main topic.So, if the sound - it's vibrations, then what varies?
Any gas - a set of specific configuration of the atoms.Unlike solids between the atoms are relatively large distance (in comparison, for example, the metal lattice).You can draw an analogy with peas, distributed over the container with the jelly-like mass.The source of sound vibrations according momentum motion nearest gas atoms.They, in turn, like balls on a billiard table, "hit" on the neighboring, and the process repeats.The speed of sound in air is precisely determines the intensity of the pulse, the underlying cause.But this is only one component.The denser the material the atoms are located, the higher the speed of sound in it.For example, the speed of sound in air is almost 10 times less than in the monolithic granite.It is very easy to understand: that the atoms in a gas would "fly" to the nearby and give him the energy of the pulse, it is necessary to overcome a certain distance.
Consequence: the temperature increases the rate of propagation increases.Although the thermal expansion rate of the atoms above the site, they move erratically and often collide.It is also true that the compressed gas carries the sound is much faster, but the champion still is a liquefied physical state.In calculating the speed of sound in gases accounted for the initial density, compressibility, and the temperature coefficient (gas constant).Actually, it all follows from the above.
Still, what is the speed of sound in air?Many have already guessed, it is impossible to give a definite answer.Here are just some of the basic data:
- at zero degrees Celsius at the zero point (the sea level), the speed of sound is about 331 m / s;
- lowering the temperature to - 20 degrees Celsius, you can "slow down" the sound waves to 319 m / s, as originally atoms in space are moving slowly;
- raising as it accelerates to 500 degrees sound propagation by almost half - to 550 m / s.
However, these are approximate, since in addition to the temperature of the gases on the ability to carry out the sound pressure is also affected by the configuration of the space (a room with objects or open space), own mobility, etc.
Currently, the property of the atmosphere to hold the sound actively investigated.For example, one of the projects makes it possible by registering the reflected sound (echo) to determine the temperature of the air layers.
