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This contest is fueled by the following news:
The Zero Gravity Corporation has been given the thumbs up by the Federal Aviation Administration to conduct "weightless flights" for the general public, providing the sensation of floating in space. Tickets are on sale for around $3,000. A specially modified Boeing 727-200 aircraft, called G-Force One, will be used during a nationwide tour Sept. 14-24. The sensation of weightlessness is created inside G-Force One by flying a parabolic flight pattern, specifically a 10,000-foot "roller coaster", which takes place at between 22,000 and 32,000 feet altitude above Earth.
The condition of complete, absolute weightlessness - zero gravity - is unattainable since apart from gravitational forces, some external or internal forces always act on the space vehicle. Forces can be caused by the functioning of every possible system and units of the vehicle, motion and movement of cosmonauts, the aerodynamic interaction of the vehicle with the outer atmosphere etc. It is possible to represent that the falling lift slightly touches the walls of the shaft.
Similar disturbing factors cause insignificant acceleration of space vehicles: rocking, vibrations, etc. Values of such micro-accelerations make a part per million free fall acceleration on Earth. Though even such insignificant disturbances lead to distortions in the results of some scientific experiments onboard, in particular, they should be taken into consideration during growth in the zero gravity of crystals.
Places exist in nature, where items are generally weightless. For example, in space, somewhere a long way from planets, from the Sun and from the stars things might be weightless. After all, any heavenly body strongly attracts towards it. If the more you move away from the heavenly body, the lesser would be the gravity of the heavenly body. Many think that the zero gravity state in a spaceship is because the ship moved away from Earth and the gravity of earth is weakened. But it is the glaring mistake. After moving away from Earth, its gravity weakens but not so quickly. We fly at an altitude of somewhere near 300km. In comparison with the huge Earth, the altitude at which we are flying is negligible. And nevertheless, weightlessness is complete while flying.
Erect a tower with a height of around 300km on the ground. Not the slightest of zero gravity conditions is felt at the top of the tower. And on the contrary, zero gravity can occur even below the ground, for example, in mines.
What exactly is happening?
There are two types of zero gravity conditions.
The loss of weight, which occurs at larger distances from heavenly bodies due to the weakening of gravity, is called static weightlessness. And the condition, in which objects exist while flying around the orbit, is called dynamic weightlessness.
Both the weightlessness conditions occur absolutely identically. The sensations of persons are the same during both zero gravity conditions. But the reasons are different.
During flights, astronauts have to deal only with dynamic zero gravity conditions.
We are discussing only dynamic weightlessness.
"Dynamic weightlessness" means "zero gravity, occurring during motion".
We feel the gravity of Earth only when we resist to it, only, when we "refuse" to fall. And as soon as we "agree" to fall, the sense of gravity instantly disappears.
Imagine that you are walking with a dog by holding it with a strap. The dog moves towards some direction and the strap is stretched. You feel the tension of the strap – the "attraction, gravity" of the dog, only while you resist. And if you follow the dog obediently, the strap sags and the sensation of pull disappears.
The same thing happens with the gravity of the Earth.
A plane is flying. Two parachutists are ready in the cabin to take a free-fall jump from the plane. The Earth pulls them downwards. And, they are resisting it by pressing the legs against the floor of the plane. The two parachutists feel the gravity of Earth – their feet are pressed against the floor with a force. The two can feel their own weight. The "Strap is under tension".
Now, both the parachutists agreed to follow the place, towards which the Earth is pulling them. Both of them stood at the edge of the hatch and jumped downwards. The strap "sags". The feel of pull towards Earth immediately disappears. Both the parachutists become weightless.
Is it hard to believe? Then imagine such a continuation of this story.
A big empty box is dropped simultaneously with two parachutists from a plane. The two parachutists, with unopened parachutes, and the empty box fly with the same speed nearby, somersaulting in the air.
One person stretched his hand and seized the nearby flying box and opened the door box and retracted inside the box.
Now, one of the two persons is flying somersaulting outside the box and the second one is flying somersaulting inside the box.
Both shall have completely different perceptions.
The one, who is flying outside, sees and feels that he is promptly flying downwards. He can hear the whistling of the wind in his ears. The distantly approaching ground is visible to him. Clouds are moving past him.
And, the one that is flying inside the box with a closed door seems to be "floating" in the box. He assumes that the box \quietly stands on the Earth and he, having lost the weight, float in the air as a fish in an aquarium.
Strictly speaking, there is no difference between both the parachutists. Both the parachutists from the rock fly towards the Earth at the same speed. But, one would have said: "I am flying" and the other would have said: "I am floating in the same place". The issue is that, one is oriented as per the Earth and the other – as per the box, in which he is flying.
That's how the state of dynamic zero gravity occurs in the cabin of a spaceship.
At the first instance, this would seem unclear. One would think that the spaceship flies parallel to the Earth as in the case of a plane. And zero gravity is not felt in a horizontally flying plane. But we already know that our space ship satellite continuously falls. It is much more similar to the box, dropped from a plane than the plane itself.