THE EVENTS OF PHYSICS IN THE STATE OF WEIGHTLESSNESS
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Archimedes´ principle
In the state of weightlessness, there is also zero buoyancy in the fluid, which arises on the surface of the Earth according to Archimedes' principle. Therefore, the flame of a burning candle is not stretched upwards, but is small, badly burning and looks like a ball. Under the influence of Archimedes' principle, hot flue gases rise on the surface of the Earth and are replaced by ambient air, which ensures the supply of oxygen to the flame. Therefore, it is also a problem to boil water in weightlessness. If I heat the liquid in the vessel, as is usual by heating the bottom of the vessel, the liquid at the bottom is heated first, but then, due to the buoyancy force, the heated one rises and is replaced by the remaining colder liquid. In a state of weightlessness, this automatic liquid mixing mechanism does not work, the liquid must be mixed manually. But on the other hand, it doesn't matter if we heat it from above or below. There is no "down" and "up.
Isolated system of objects
On the surface of the Earth, we are in constant contact with the Earth, we are attracted to it by gravity force and we gain support thanks to the friction between the soles of our shoes and the surface on which we stand. In most activities, we unknowingly and completely automatically use the fact that we transfer part of the energy and momentum to the Earth by force. During the jump, we bounce off the Earth and thus gain a power impulse upwards. In the state of weightlessness, the possibility of bounce is less smaller. When hitting with a hammer, we act with a hammer on the object, but thanks to the reaction, this object acts on the hammer and gives it an impulse backwards. This reaction is eliminated by the force of the Earth, because "we stand firmly on the ground." In the state of weightlessness, after striking with an ordinary hammer, the astronaut flies away from the place of impact in the opposite direction. When manipulating a rotary wrench, the momentum is also gained by the tool and the person handling it. On the surface of the Earth, we are actually rotating the whole Earth, which, of course,"does not even move". At the space station, trying to tighten the screw with a wrench means turning the astronaut in the opposite direction. An astronaut who would pick up a table fan and turn it on will also spin in the opposite direction to the fan propellers. (Fortunately, it happens at a slower speed, which depends on the ratio of the moments of inertia of both objects.)
Use of weightlessness
The use of weightlessness is currently still in the experimental stage. It is already clear that the state of weightlessness is ideal for the smoother growth of some types of single-crystals, in which the gravity force can cause an uneven distribution of various heavy particles or, in general, crystal lattice defects. In this way, for example, new types of semiconductors can be formed. Even some organic substances create a more perfect and regular structure in a state of weightlessness, which is already used in the development of better quality drugs. Like crystals, it is possible to produce more perfect alloys in weightlessness. Experiments are underway with the weightless burning process, which may result in the improvement of internal combustion engines on Earth, as well as in the preparation of new types of hydrocarbon fuels.