Biography of Ernest Mach

Biography of Ernest Mach

Biography of Ernest Mach

Biography of Ernest Mach Introduction to the life of Ernest Mach, biography of Ernest Mach Biography of Ernest Mach Ernest Mach Born February 18, 1838 Brno, Austrian Empire Death 19 February 1916 (78 years) Munich, German Empire Austrian nationality Descent of physics Graz University Workplace Carlf University Graduate of the University of Vienna

The reason for the popularity of Mach number

Religion without God

Religion without God

Ernst Waldfried Josef Wenzel Mach (German: Ernst Waldfried Josef Wenzel Mach) Biography of Ernest Mach was a famous Austrian philosopher and prominent physicist of the nineteenth and twentieth centuries.

The Life Of Ernest Mach

He was born in Toras. He has valuable theories in classical mechanics, was one of the pioneers of Albert Einstein’s theory of relativistic mechanics, and published his theories in two volumes, Mechanics.

Mach was chair of history and inductive theory at the University of Vienna. His main job was to further cultivate the empiricism of Barclay and Hume.

After completing his education, he started teaching. Mach at this time criticized the principles of classical mechanics and developed new theories known as his own. He also researched the physiology and psychology of human emotions and especially their relationship with the theory of science. Mach is one of the founders of the empiricist school of theism, which is based on a realistic philosophy based on the analysis of human feelings and emotions.

Although Mach was a master of physics, he is still best known as a philosopher of science. He believed that any scientific theory that referred to objects and could not return them to sensory experiences was rejected. Mach, meanwhile, believes that science must turn a blind eye to concepts such as absolute space and absolute time. This aspect of Mach’s views has had a profound effect on the famous twentieth-century physicist Albert Einstein.


According to Ernst Mach, in science, only words that are empirically observable should be used, and in scientific theories, words such as electric field cannot be used. This view is sometimes referred to as crude empiricism.

The first philosophers of science, and most physicists and mathematicians inclined to logic and philosophy, did not follow Mach.


Ernest Mach died on October 29, 1916.

Familiarity with Mach number

The Mach number is named after Ernst Mach, the Czech-Austrian philosopher and physicist. It is placed.

To write two Machs, instead of Mach 2, Mach 2 is used. The word is somewhat Biography of Ernest Mach reminiscent of Mark’s old deep-sea modern unit of synonym Qolaj, which originated earlier than Mach and probably influenced the use of the word Mach. A decade before humans flew faster than sound, aeronautical engineers used the word Mach number to refer to the speed of sound, not Mach.

Dimensional review

Mach numbers are used for both high-velocity objects moving in a fluid and high-velocity fluid flows in channels such as nozzles, diffusers, or wind tunnels. Since this number is a ratio of two velocities, it is a dimensionless number.

At 15 degrees Celsius, the speed of sound in the Earth’s atmosphere is equal (761.2mph, 340.3m / s). The velocity indicated by the Mach number is not a fixed number. For example, this speed depends on temperature and atmospheric composition. Regardless of altitude, this velocity remains constant in the air’s stratosphere, although air pressure changes with altitude.

Ernest Mach Biography, Ernest Mach Biography
Familiarity with Mach number

Temperature dependence

Since the speed of sound always increases with increasing temperature, the actual speed of an object moving at a Mach speed will depend on the temperature of the fluid around it.

Mach number is useful because fluid behaves similarly in a similar Mach number. Thus, an aircraft flying at Mach 1’s surface receives the shock wave in the same way as it would if it flew at a Mach speed of 11,000 m, albeit at a speed of 295 m / s. , 654.6mph Biography of Ernest Mach (speed at sea level) flies.

High-velocity flows around flying objects can be inaccurately classified into five categories:

– Subsonic:

M <Mcri

– Near sound (Transonic):

Mcrit <1 (e.g .: 0.8 <M <1

– Audio (Sonic)

M = 1

– Above the sound (1 <M <5: (Supersonic

the required speed

– Supersonic (M> 5: (Hypersonic

For comparison: the required speed for low ground orbit in the air and high altitude is approximately 7.5 km / s = 25.4. The speed of light in a vacuum is approximately Mach 88,000.

At high speeds of sound, the flow field around the object includes both the lower and upper parts of the sound. The upper time range of sound begins when the first areas of current M> 1 appear around the object.

If there is an airfoil (for example, an airplane wing), this usually happens at the top of the wing. Upstream sound can only be reduced to low sound in a normal shock, usually before it reaches the back edge.

As the speed increases, the flow areas M> 1 on the back and front edges also increase. When the velocity reaches and exceeds M = 1, ordinary doubt reaches the back edge and becomes a weak and indirect doubt. The current decreases after suspicion but remains in the upper range of the sound. A typical suspicion arises in front of the object, and the only subsonic area in the flow field is a small area around the back edge of the object.

1- Mach number in the air flow above the sound around an airfoil, M <1 (a) and M> 1 (b).

When an aircraft reaches a Mach speed, a large pressure difference occurs directly in Biography of Ernest Mach front of the aircraft. This difference in pressure is called a shock wave, which propagates backward and out of the plane and has the shape of a cone (Mach cone).

This shock wave causes a sound explosion that can be heard when a plane passes over a person’s head at high speed. The person inside the plane will not hear this sound. The higher the speed, the narrower the cone will be, and after reaching M = 1 it will look less like a cone, but more like an almost concave plane.

At very high speeds of sound, the shock wave begins to form its conical shape and the current is completely above the sound, or (if the object has no tip) only a very small range of subsonic current between the nose of the object and the shock wave it creates. , Remains (if the object is sharp, there is no air between the nose and the shock wave, the shock wave starts from the nose itself).

As the Mach number increases, so does the shock wave strength, and the Mach cone becomes increasingly narrow. As the flow of sialase passes through the wave, its velocity decreases and temperature, pressure and density increase.

The stronger the shock, the larger the changes. At a very high Mach number after the shock, the temperature rises so much that ionic decomposition and the separation of gas molecules begin behind the shock wave. Such currents are called ultrasonic.

It is clear that any object moving at supersonic speeds is also exposed to the same intense temperature as the gases behind the nose shock wave, and therefore the choice of heat-resistant materials is important.

Familiarity with Mach number, Ernest Mach ideas
Biography of Ernest Mach

High-speed flow in a channel

When a current in a channel passes M = 1, it rises above the sound, a big change also occurs. Normally, one expects the velocity of the current to increase by contracting the channel. This is true at the speed below the sound. , But when the current is high, the relationship between the current range and the velocity is reversed.

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