Weightlessness is capable of such emotions. School encyclopedia. The effect of weightlessness on the body

Weight as the force with which any body acts on a surface, support or suspension. Weight arises due to the gravitational attraction of the Earth. Numerically, the weight is equal to the force of gravity, but the latter is applied to the center of mass of the body, while the weight is applied to the support.

Weightlessness - zero weight, can occur if there is no gravitational force, that is, the body is sufficiently away from massive objects that can attract it.

The International Space Station is located 350 km from Earth. At this distance, the acceleration of gravity (g) is 8.8 m/s2, which is only 10% less than on the surface of the planet.

This is rarely seen in practice - gravitational influence always exists. Astronauts on the ISS are still affected by the Earth, but there is weightlessness there.

Another case of weightlessness occurs when gravity is compensated by other forces. For example, the ISS is subject to gravity, slightly reduced due to distance, but the station also moves in a circular orbit at escape velocity and centrifugal force compensates for gravity.

Weightlessness on Earth

The phenomenon of weightlessness is also possible on Earth. Under the influence of acceleration, body weight can decrease and even become negative. The classic example given by physicists is a falling elevator.

If the elevator moves downward with acceleration, then the pressure on the elevator floor, and therefore the weight, will decrease. Moreover, if the acceleration is equal to the acceleration of gravity, that is, the elevator falls, the weight of the bodies will become zero.

Negative weight is observed if the acceleration of the elevator movement exceeds the acceleration of gravity - the bodies inside will “stick” to the ceiling of the cabin.

This effect is widely used to simulate weightlessness in astronaut training. The aircraft, equipped with a training chamber, rises to a considerable height. After which it dives down along a ballistic trajectory, in fact, the machine levels off at the surface of the earth. When diving from 11 thousand meters, you can get 40 seconds of weightlessness, which is used for training.

There is a misconception that such people perform complex figures, like the “Nesterov loop,” to achieve weightlessness. In fact, modified production passenger aircraft, which are incapable of complex maneuvers, are used for training.

Physical Expression

The physical formula for weight (P) during accelerated movement of a support, be it a falling bodice or a diving aircraft, is as follows:

where m is body mass,
g – free fall acceleration,
a is the acceleration of the support.

When g and a are equal, P=0, that is, weightlessness is achieved.

In space, weightlessness is a constant condition of life and activity. This sharply distinguishes space from the environment in which humanity lives. On Earth, a person constantly struggles with the force of gravity, so the loss of his own weight is unusual for him, and a person has no experience of being in weightlessness.

Yes, you can occasionally experience weightlessness: for example, while flying on an airplane, when it falls into “air pockets” or suddenly loses altitude. Skydivers know the feeling of weightlessness well. Weightlessness- a state in which there is no force of interaction between the body and the support.

In conditions of weightlessness on board a spacecraft, many physical processes (convection, combustion, etc.) proceed differently than on Earth. The absence of gravity requires a special design of systems such as showers, toilets, food heating systems, ventilation, etc. To avoid the formation of stagnant zones where carbon dioxide can accumulate, and to ensure uniform mixing of warm and cold air, the ISS, for example, has a large number of fans installed. Eating and drinking, personal hygiene, working with equipment and, in general, ordinary everyday activities also have their own characteristics and require the astronaut to develop habits and the necessary skills. The effects of weightlessness are taken into account in the design of a liquid-propellant rocket engine designed to launch in zero gravity.

How does weightlessness affect a person?

When transitioning from the conditions of earth's gravity to conditions of weightlessness, most astronauts experience an organism reaction called space adaptation syndrome. The symptoms of this condition are similar to seasickness: loss of appetite, dizziness, headache, increased salivation, nausea, sometimes vomiting, spatial illusions. All these effects usually disappear after 3-6 days of flight. During a long-term (several weeks or more) stay of a person in space, the lack of gravity begins to cause certain changes in the body that are negative in nature: rapid muscle atrophy - the muscles are actually turned off from human activity, as a result all the physical characteristics of the body decrease; the consequence of a sharp decrease in the activity of muscle tissue is a reduction in the body’s oxygen consumption; due to the resulting excess hemoglobin, the activity of the bone marrow, which synthesizes hemoglobin, may decrease; limited mobility disrupts phosphorus metabolism in the bones, which leads to a decrease in their strength.

The human body, once in conditions of weightlessness, begins to rebuild. A man is losing weight. The whole body becomes flabby, as if lying in bed for a long time. The bones become fragile - they do not experience stress here. Muscles work little. And from inactivity all organs weaken. It's like a person who has been in bed for several months learning to walk again. Cosmonauts Nikolaev and Sevastyanov, after eighteen days of being in weightlessness, could not get to their feet at first.

To reduce the harmful effects of weightlessness, scientists have come up with various means: they recommend that astronauts do more physical exercise in space, mainly with expanders. We created special “penguin” load-bearing suits for astronauts. These tight-fitting suits have elastic bands sewn into them that tighten the body into a tight ball. To stay upright in such a suit, you have to slightly tense your muscles all the time. And this is exactly what is needed so that they do not weaken.

They also make a “treadmill” at orbital stations. In order not to float away, the astronaut fastens himself with elastic bands. They replace the astronaut’s weight, pull him by the belt and shoulders down to the floor, and press him to the “track.” She runs back under the astronaut. And he runs forward along it. Not everyone easily tolerates weightlessness, especially at first. Many people feel like they have been hung upside down. Some people experience nausea. The first day or two, astronauts usually get used to weightlessness.

Weightlessness occurs when a spacecraft enters orbit. But the disappearance of weight should not be confused with the disappearance of gravitational attraction - for example, on the International Space Station (at an altitude of 350 km) it is only 10% less than on Earth. The state of weightlessness on the ISS arises not due to the lack of gravity, but due to movement in a circular orbit at the first escape velocity, that is, the cosmonauts seem to constantly “fall forward” at a speed of 7.9 km/s.

How astronauts are trained in zero gravity on Earth

On Earth, for experimental purposes, it is possible to create a short-term state of weightlessness (up to 40 seconds) when an aircraft flies along a parabolic trajectory. To achieve this effect, the aircraft must have a constant downward acceleration g (zero g). Such an overload can be created for a long time (up to 40 seconds) by performing a special aerobatics maneuver (“failure in the air”). The pilots sharply lower the altitude; at a standard flight altitude of 11,000 meters, this gives the required 40 seconds of “weightlessness”; Inside the fuselage there is a chamber in which future cosmonauts train; it has a special soft coating on the walls to avoid injuries when gaining and losing altitude. A person experiences a feeling similar to weightlessness when flying on civil aviation flights upon landing. But for the sake of flight safety and the heavy load on the aircraft structure, civil aviation drops the altitude gradually, making several long spiral turns (from a flight altitude of 11 km to an approach altitude of about 1-2 km). Those. The descent is carried out in several passes, during which the passenger only feels for a few seconds that he is being lifted up from the seat. The state of weightlessness can be felt at the initial moment of free fall of a body in the atmosphere, when air resistance is still small.

What is weightlessness? Floating cups, the ability to fly and walk on the ceiling, and move even the most massive objects with ease - such is the romantic idea of ​​this physical concept.

If you ask an astronaut what weightlessness is, he will tell you how difficult it is during the first week on board the station and how long it takes to recover after returning, getting used to the conditions of gravity. A physicist, most likely, will omit such nuances and reveal the concept with mathematical precision using formulas and numbers.

Definition

Let's begin our acquaintance with the phenomenon by revealing the scientific essence of the issue. Physicists define weightlessness as a state of a body when its movement or external forces acting on it do not lead to mutual pressure of particles on each other. The latter always occurs on our planet when any object moves or is at rest: it is pressed by gravity and the oppositely directed reaction of the surface on which the object is located.

An exception to this rule is cases of falling at the speed that gravity imparts to the body. In such a process, there is no pressure of particles on each other, weightlessness appears. Physics says that the condition that occurs in spaceships and sometimes in airplanes is based on the same principle. Weightlessness appears in these devices when they move at a constant speed in any direction and are in a state of free fall. An artificial satellite or delivered into orbit using a launch vehicle. It gives them a certain speed, which is maintained after the device turns off its own engines. In this case, the ship begins to move only under the influence of gravity and weightlessness occurs.

At home

The consequences of flights for astronauts do not stop there. After returning to Earth, they have to adapt back to gravity for some time. What is weightlessness for an astronaut who has completed his flight? First of all, it's a habit. Consciousness for some period still refuses to accept the fact of the presence of gravity. As a result, there are often cases when an astronaut, instead of putting a cup on the table, simply let it go and realized the mistake only after hearing the sound of dishes breaking on the floor.

Nutrition

One of the difficult and at the same time interesting tasks for the organizers of manned flights is to provide astronauts with food that is easily digestible by the body under the influence of weightlessness in a convenient form. The first experiments did not arouse much enthusiasm among the crew members. An indicative case in this regard is when the American astronaut John Young, contrary to strict prohibitions, brought a sandwich on board, which, however, they did not eat, so as not to violate the regulations even more.

Today there are no problems with diversity. The list of dishes available to Russian cosmonauts includes 250 items. Sometimes a cargo ship departing for the station will deliver a fresh meal ordered by one of the crew.

The basis of the diet is All liquid dishes, drinks, and purees are packaged in aluminum tubes. The packaging and packaging of products is designed in such a way as to avoid the appearance of crumbs that float in weightlessness and could get into someone’s eye. For example, cookies are made quite small and covered with a shell that melts in your mouth.

Familiar surroundings

At stations like the ISS, they try to bring all conditions to those familiar on Earth. These include national dishes on the menu, air movement necessary both for the functioning of the body and for the normal operation of equipment, and even the designation of the floor and ceiling. The latter has, rather, psychological significance. An astronaut in zero gravity does not care in which position to work, but the allocation of a conditional floor and ceiling reduces the risk of loss of orientation and promotes faster adaptation.

Weightlessness is one of the reasons why not everyone is accepted as an astronaut. Adaptation upon arrival at the station and after returning to Earth is comparable to acclimatization, enhanced several times. A person with poor health may not be able to withstand such a load.

To the question: what is weightlessness? under what conditions does it occur? given by the author Marty_Ray_ka the best answer is Weightlessness is a state of a body when only gravitational forces act on it, and the external gravitational field does not cause pressure from one part of the system on another and their deformation. In a state of weightlessness, the metabolism and blood circulation of a living organism change somewhat. Weightlessness occurs when a body is in free fall and in spaceships when they move with their engines turned off.

Answer from Phantom[guru]
when the body has no weight. either in space or in free fall, the body is in weightlessness.

Answer from Komerrsant[guru]
Weight is the force with which a body acts on any support, which means weightlessness, (in its own words) this is the state of the body when it does not press on the support. If there is not enough information in WIKI, look

Answer from User deleted[guru]
Weightlessness is a state when the force of interaction of a body with a support (body weight), arising in connection with gravitational attraction, the action of other mass forces, in particular the force of inertia that arises during the accelerated movement of a body, is absent. Sometimes you hear another name for this effect - microgravity - but this name is incorrect! ! - gravity (force of attraction) remains the same.
Quite often the disappearance of weight is confused with the disappearance of gravitational attraction. This is wrong. An example is the situation on the International Space Station (ISS). At an altitude of 350 kilometers (the altitude of the station), the acceleration of gravity is 8.8 m/s², which is only 10% less than on the surface of the Earth. The state of weightlessness on the ISS occurs due to movement in a circular orbit at the first escape velocity.
On Earth, for experimental purposes, a short-term state of weightlessness (up to 40 s) is created when an aircraft flies along a parabolic plane (and in fact, ballistic, that is, the one along which the aircraft would fly under the influence of the force of gravity alone; this trajectory is a parabola only if at low speeds; for a satellite it is an ellipse, circle or hyperbola) trajectory. The state of weightlessness can be felt at the initial moment of free fall of a body in the atmosphere, when air resistance is still small.
To understand the essence of weightlessness, you can consider an airplane flying along a ballistic trajectory. These are used to train astronauts in Russia and the USA. In the cockpit, a weight is suspended from a string, which usually pulls the string down (if the plane is at rest or moving uniformly and in a straight line). When the thread on which the ball hangs is not taut, a state of weightlessness occurs. Thus, the pilot must control the plane so that the ball hangs in the air and the thread is not taut. To achieve this effect, the plane must have a constant downward acceleration g. Thus, we can say that the plane “falls” along with the ball, string, pilot and astronauts.
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Weight and its perception
Weightlessness is the state of the body when it is under the influence of only mass forces. For example, under the influence of gravity alone. Movement under the influence of gravity alone is also called free fall.
If, in addition to mass forces, surface forces act on the body, for example, the reaction of support, a state of weightiness arises.
Body weight is the force with which the body acts on a support or suspension.
What people perceive as weight is only a consequence of the reaction of the support or environment on their bodies.
The force acting on different parts of a body located on Earth is not the same. If we conditionally divide the body into horizontal layers, then we can imagine that each layer, in addition to the reaction of the underlying support, will also be affected by pressure from the layers located above. A person feels a similar pressure difference as weight.
A body placed in a hermetically sealed container experiences a state of weightlessness during free fall experiments (for example, dropped from a high tower). This happens because the acceleration of the container, the air enclosed inside it, and all parts of the body itself, caused by the influence of gravity, is the same, the support reaction and pressure gradient are absent (in the case of a free fall of a body outside the container, this is not entirely true, except for the force of gravity on it The reaction of the external environment also acts - the force of air resistance).

Probably each of us has experienced a feeling of weightlessness in our lives. Let's look at what weightlessness is, how it is achieved and where you can experience it.

When answering the question of what weightlessness is, many will remember the force of gravity and the possibility of free flight, walking on the ceiling, flying objects and astronauts who most often experience this feeling.

To discuss the concept of weightlessness, I propose to discuss the scientific part of the issue and the physical phenomenon. On planet Earth, objects and living beings have a force of attraction (gravity). Thus, if an object moves or is at rest, the gravity of the object exerts pressure on the surface.

Weightlessness is a state of the body in which the force of interaction with the surface is significantly small and there is no pressure on each other. Often, when defining weightlessness, the concept of gravity or microgravity is used.

Interesting facts about weightlessness and gravity

What do you and I know about weightlessness, how can we characterize this phenomenon?

Inconvenience.

Currently, the phenomenon of weightlessness has been fully studied and does not raise many questions. Before the flight, astronauts spend a long period of time preparing their bodies for weightlessness, and despite this, the lack of gravity puts the body under quite a lot of stress.

The main disturbance in the phenomenon of weightlessness is observed in changes in fluid pressure in the body, especially blood. In addition, there is no usual load on the musculoskeletal system, which causes discomfort. After an astronaut is delivered to the space station, his body goes through a period of adaptation for some time, despite many months of preparation before the flight.

The effect of weightlessness on the body

Typically, the body's adaptation period takes place within 7-10 days. As a result, due to the lack of gravity, astronauts lose weight, their performance decreases, and the overall fatigue of the body increases. The ratio of elements in tissues may also change. After a long stay in space, a person can become several centimeters due to weightlessness. As a result, pinched nerves may occur and various muscle and joint pains may appear.

Nutrition.

Today, astronauts have a very varied diet. The diet consists of freeze-dried products packaged in aluminum tubes. Almost all food is in the form of purees. The diet and containers are thought out in such a way as to avoid crumbs and their contact with the eyes. The cookies are made small so as not to bite, and the top is covered with a shell.

Ways to experience the feeling of weightlessness in theory and practice

The feeling of weightlessness can be fully experienced in space, but for this you need to choose this profession and prepare for many years. However, the feeling of weightlessness can also be experienced on Earth, albeit insignificant.

On Earth, weightlessness can be simulated in the following way. For experimental purposes and for training, the astronaut was created in a state of weightlessness for up to 40 seconds using a special aircraft that was exposed only to the force of gravity. The plane's trajectory follows a parabola. Such sensations can now be experienced on special simulators and in amusement parks. The essence is that the height is sharply gained and then dropped just as sharply, causing a feeling of free fall, weightlessness.

We experience similar sensations on civil aviation flights during the landing period, as well as in a car, with a sharp change in movement from top to bottom.

In addition, similar sensations can be obtained by jumping on a trampoline, while being in the air from the jump just before falling down, in modern high-speed elevators with a sharp stop on a high floor.

Now there are special weightlessness simulators in which you can experience this sensation on board an IL-76 aircraft specially equipped for these needs. This is a special laboratory designed for testing overloads, including by astronauts before space flights. During the flight, the altitude rises sharply and at an altitude of 8-9 km the pilot turns off the power of the engines, thereby allowing the aircraft to move by inertia. Just when the force of gravity becomes equal to the force of inertia, weightlessness is achieved. During the flight, the group experiences several such sensations of weightlessness on board the aircraft. The cost of such a flight is individual and can be combined with an excursion, space meals and much more.

Conclusion

The phenomenon of weightlessness can mainly be experienced while in space, but we also periodically experience it on an airplane, on an attraction, in an elevator and even on a trampoline, although it lasts literally seconds.