Why is weightlessness in space, why is it that people are weightless in space?

Weightlessness in space comes from the space shuttle.

and centrifugal force of the space station's movement in orbit.

These centrifugal forces acting on the space shuttles and astronauts happen to be equal to the gravitational pull of the Earth and in opposite directions.

Therefore, neither the space shuttle nor the Mir space station will fall to Earth. It must be orbited at an exact set speed at an orbit that is at a proper distance from the Earth so that the Earth's gravitational pull is comparable to the centrifugal force generated by the Space Shuttle's orbit. Gravity is produced due to the vector difference between the gravitational and centrifugal forces of the earth.

When the astronaut rotates around the earth at a uniform speed in space, the gravitational force of the earth on the astronaut is equal to the centrifugal force produced by the rotation and is in the opposite direction, so the astronaut does not feel the presence of any gravity, which is complete weightlessness.

Sometimes abbreviated as weightlessness.

When the acceleration of a near-Earth object is downward, its apparent weight is less than the actual gravity, we call it weightless, and when the object accelerates downward with acceleration g (that is, free fall), we call it completely weightless.

In order for a satellite or spacecraft to orbit the earth, it must reach a certain speed, which is called the first cosmic velocity, also called orbital velocity, which is about 7 9 kilometers a second at an altitude near the ground, and if the orbit is high, the speed can be appropriately reduced.

Referring to the figure below, the orbital motion of the spacecraft, in a short distance, can be regarded as a flat throwing motion, that is, the spacecraft flies at a certain horizontal speed, and at the same time is subjected to the gravity of the earth, and does free fall in the vertical direction. (At a large distance, because the direction of gravity is changing, it can be seen as a superposition of a series of short-distance flat throwing motions.) ）

When the horizontal motion reaches a certain speed, because the earth is a sphere, the surface has a certain arc, and the distance it falls can just match the arc of the earth, and the spacecraft can do orbital motion.

In fact, when the spacecraft flies in space, it will still be affected by some and its thin atmosphere, so it is only doing an approximate flat throwing motion (which is the superposition of approximate uniform linear motion and approximate free fall), so the spacecraft is not completely weightless, but in a state of microgravity.

We have weight because the earth is attractive, the earth is attracting us, when we go to space, we are too far away from the earth, the power of the earth cannot act on us, so we have no gravity, so we are weightless and floating.

First of all, it is explained that "weightlessness" in space is not weightlessness in the true sense. Rather, it is a special state similar to weightlessness.

The definition of weightlessness is a phenomenon in which the pressure of an object on a support is less than the gravitational force experienced by the object. If you think about it carefully, you will find that this definition sets a premise for the phenomenon of weightlessness, that is, the existence of a gravitational field. Without a gravitational field, there is no gravity, and there is no weightlessness.

In other words, according to this definition, weightlessness occurs only within the gravitational pull of celestial bodies. For space without a gravitational field (which is negligible or equilibrium with centrifugal acceleration, it is all included in the absence of a gravitational field), there is no weightlessness according to the above definition due to the absence of gravity. The state of gravity in space, on the other hand, is also customarily called weightlessness because it feels similar to weightlessness.

The state of "weightlessness" in space is a state of detachment from the force field, or the state of complete absence of gravity. This is known from the situation of the astronaut levitating on the spacecraft.

Why are people weightless in space? In fact, it is not that gravity disappears, but that it is transferred.

Weightlessness is not the loss of gravity, but people in space have to make a circular motion around the earth, and the circular motion requires a centripetal force, and this centripetal force is provided by the gravitational force (gravity) of the earth on people. In other words, the gravitational force exerted on man in space is used to maintain man's circular motion around the earth.

Because space loses the gravitational pull of the earth, people cannot stand, so they are weightless.

Because the earth is attractive to people who can walk upright. And outer space has no gravity, only buoyancy, so when you get to outer space, you will be weightless, and many things will float.

This is because there is no gravitational force, and there is no gravitational force in space, so this is the case.

Because there is no gravitational force in space, a person is weightless in space.

1.Objects in space are the cause of total weightlessness: in space, the movement of objects has a centrifugal effect on the center of the Earth.

Because the centripetal force and the centrifugal force are two opposite forces, if the centrifugal force is greater than the centripetal force, the object will move away from the earth. If the centrifugal force is less than the centripetal force, the object will move close to the earth. If the centrifugal force is equal to the centripetal force, the object will move in a circular motion towards the earth.

Because when an object orbits the earth in a circular orbit, the centrifugal force is equal to the centripetal force, i.e., the gravitational force is equal to the centrifugal force. When gravity fails, objects in space are completely weightless.

2.In the vicinity of the Earth, weightlessness occurs when an object has a vertical downward acceleration. Whereas, total weightlessness refers to a situation where the acceleration of an object is equal to the acceleration due to gravity, at which point it receives zero support or pulling force.

Weightlessness in space comes from the centrifugal forces of the space shuttle and space station moving in orbit, and when the astronauts rotate around the Earth at a uniform speed in space, these centrifugal forces acting on the shuttle and astronauts happen to be equal to the gravitational force of the Earth and in the opposite direction. So the astronaut doesn't feel the presence of any gravity, which is complete weightlessness. Therefore, neither the space shuttle nor the Mir space station will fall to Earth.

Weightlessness has a great impact on the human body, and in addition to causing astronaut bone loss, it can also lead to muscle relaxation, decreased immunity, and aging in astronauts. Due to the loss of gravity, the facial moisture will increase, and the eye sockets will be swollen, the facial edema, the plasma volume will be reduced, the intracellular fluid will be lost, and the cardiovascular function in the human body will change, causing a variety of spatial motion sickness.

All objects on Earth are subject to the gravitational pull of the Earth, which is called gravity. The magnitude of gravity decreases rapidly as the altitude increases. When spacecraft orbit the Earth or fly in interplanetary space orbit, they are far away from the Earth and other planets and are naturally in a state of loss of gravity, which is weightlessness.

Of course, weightlessness is not absolutely devoid of gravity, but gravity is very small, so weightlessness is often called microgravity.

Weightlessness is a very important characteristic of the space environment.

In weightlessness, the human body and other objects can float with a small force. Weightlessness enables scientific research and material processing in space that are difficult or impossible to achieve on the ground, such as the growth of high-purity large monocrystalline silicon, the manufacture of ultra-pure metals and superconducting alloys, and the manufacture of special biopharmaceuticals.

Weightlessness also provides favorable conditions for assembling large spacecraft (such as space stations, space solar power plants, etc.) in space.

Of course, weightlessness will also cause some harm to the human body, mainly because astronauts will suffer from space motion sickness. The disease is typically characterized by paleness, cold sweats, nausea and vomiting, and sometimes increased saliva, epigastric discomfort, drowsiness, headaches, loss of appetite, and flirtatious delusions. Long-term weight loss can also lead to osteoporosis and muscle atrophy in the body.

In order to prevent and slow down space motion sickness, it is first necessary to strengthen the training of astronauts on the ground and enhance their physical fitness; In addition, physical exercise is important in space, and when we watch live videos about space activities on TV, we often see astronauts in space moving their bodies on sports equipment.