# How fast is one Mach? How much is it converted to kilometers per hour?

2021-09-11 | Scientific Black Hole Original Collection0 |

In a sense, Mach is a physical quantity that represents the speed of movement of an object, but it is a relative value. It is a value obtained by dividing the flying speed of an object by the speed of sound, so Mach 1 can represent the speed of sound. But we knowThe speed of sound is related to many factors. For example, when the temperature is 15 degrees Celsius under standard atmospheric pressure in the air, the speed of sound propagation is 340m/s, which means that when one Mach is 15 degrees Celsius under standard atmospheric pressure, it is 340m/s, if converted to kilometers.Every hour is 1224 kilometers per hour.

The speed of vehicles in our daily life is rarely expressed by Mach. Its application is mainly in the aerospace and military fields, such as the speed of space shuttles, fighter jets and even missiles.

The practical significance of "Mach"

We can know that the Mach is obtained by dividing the two speeds, the flying speed of the object and the specific speed of sound, where the speed of sound varies, and it is linked to many conditions. In fact, this is also very easy to understand, we all know thatWhen exploring the universe, because the space scale of the universe is very large, the length is expressed in meters, kilometers, etc., and the front value is too large, so scientists set up a new concept to express the distance, such as the distance between the earth and the sun.The average distance of is 150 million kilometers. Scientists express this distance between the sun and the earth as an astronomical unit.

But this is not enough to express the size of the entire universe, so there is a light-year, which means the distance of light flying in one year, in addition to the parsec, the thousand parsec, etc., they are all distance units, Only used more in the field of cosmology, not used in daily life at all.

In fact, the Mach is probably the same meaning, with the speed of sound as the basic "unit", when the moving speed of the object is relatively fast, it is expressed by several Mach, which is several times the speed of sound, but at this time, it is necessary to determine the speed of the sound.How much, it can be 340m/s under standard conditions. But if the rocket is far away from the surface of the earth, the atmosphere becomes very thin, and the temperature and pressure change one after another, then the speed of sound will naturally change.

But through the Mach way of expressing speed, we can understand the real speed of an object. For example, if it exceeds 1 Mach, it means supersonic flight. If it is greater than or equal to 5 Mach, it means supersonic flight. But nowVery few human aircrafts reach this speed, and intercontinental missiles are one of them.

The origin of "Mach"

Ernst Mach is actually the name of an Austrian scientist. He has studied extensively throughout his life. He is a famous physicist, philosopher of science, and historian of science. His influence is reflected in many disciplines, especiallyIt is the physics of the 20th century. Ernst Mach made a lot of contributions. Einstein once regarded himself as a student. We know that Einstein put forward the special theory of relativity and general relativity, and he was an epoch-making and pioneering physicist.

And Planck was also a fanatical believer of Ernst Mach when he was young. You must know that the two pillars of physics in the 20th century, the theory of relativity and quantum mechanics, began with Einstein and Planck, and these twoScientists regard themselves as students of Ernst Mach. Of course, there were disagreements in the later period. There were several years of controversy between Planck and Mach.

The same is true between Einstein and Mach. Einstein has repeatedly stated that "Mach is a pioneer of general relativity, and his understanding and views on the Newton bucket experiment have a great influence on me", but Mach refused to admit itEinstein said that he believed that the theory of relativity became more and more dogmatic.

The greatness of Mach lies in his indestructible skepticism and permanent independence, which played a vital role in that period when science was booming. Mach was the first to use and introduce this unit, so he used hisName it by name.

Application of Mach number

This speed unit is not usable in daily life, but with the development of human technology, the speed of aircraft is getting faster and faster, especially in the aerospace and military fields, the Mach number is very important.

It represents the ratio of speed to sound speed, which is an indeterminate number. Therefore, when applying Mach number, the flying altitude of the aircraft and atmospheric conditions must be emphasized, so that the speed of sound in that environment can be clearly known.Only then can the real flight speed of the aircraft be determined.

When the flight speed is less than Mach 1, especially at Mach 0.6-0.8, it is generally called subsonic flight. When the flight speed exceeds Mach 1 but less than Mach 5, it is called supersonic flight.Supersonic flight above Mach 5 means supersonic flight. At present, supersonic flight of aircraft is not common.

Said at the end

In fact, the application of Mach is very important, especially in some high-speed fighters. It is necessary to know that the aircraft will resonate when flying close to the speed of sound. At that moment, the airflow through the wings and the surface of the fuselage becomes very turbulent.This will increase the difficulty of the aircraft's control and the aircraft will shake violently.

If we use the normal speed unit m/s or km/h to express the speed, then the pilot cannot accurately grasp the timing of the sonic boom and sound barrier, and cannot prepare in advance. Because of different flight altitudes and flight conditions, The speed of sound changes.

If the Mach number is used to express the flight speed, then no matter how the speed of sound changes, we only need to know that the aircraft will fly at supersonic speed when the speed is close to Mach 1, so many aircraft have "Mach" meters. Let us accurately grasp the supersonic speed.The timing of the speed of sound.

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