If you have ever been on a roller coaster you know that as it heads up and over to the top you feel as though you are going to fly out of your seat. It is the same weightless feeling and is due to the combination of speed and the curvature of the roller coaster as it is coming down. And yet, you are, indeed falling from the top of the roller coaster.
The same principles of physics that apply to the roller coaster, apply to the astronauts out in space: speed, combined with falling toward something that is curving away can seem like weightlessness. And what about the Earth itself? Why does it orbit the Sun?
It orbits because there is a gravitational force between the two objects. There is an interaction even though there is no air between them. Maybe I should talk about how you feel weight. What is your apparent weight? Let me go ahead and say that what you are feeling right now isn't really gravity. Suppose I start with some examples. Example 1: Go stand in an elevator. Do not push the buttons. Just stand there so that the elevator is at rest. How do you feel? Here is a diagram.
Since you are at rest and staying at rest, you are in equilibrium acceleration is zero. If your acceleration is zero, the net force must also be zero technically, the zero vector. The two forces on you are the force from the floor pushing up and gravitational interaction with the Earth pulling down.
The magnitudes of these two forces have to be equal in order for the net force to be zero. Example 2: Now push the "up" button. During the short interval that the elevator accelerates upwards, how do you feel? Or maybe you feel a tad bit heavier. If your elevator is like the one in this building, you might feel frustrated at how slow the damn thing goes.
And what's that funny smell? Here is a diagram for the upward accelerating elevator and you. In terms of forces, what has to be different? If the person is accelerating upwards, the net force must also be upwards. Using the same two forces as above, there are two ways this can happen. Since the gravitational force depends on your mass, the Earth's mass and the distance between those, it doesn't change.
This means that the floor must push harder on you. But wait, you feel heavier and yet the gravitational force is the same. Example 3: You are nearing the top floor and the elevator has to stop.
Since it was moving up, but slowing down it has to accelerate in the downward direction. Now the net force must be in the downward direction. Again, the magnitude of the gravitational force doesn't change. The only thing that can happen is for the floor to push less. From this, you feel lighter. Last Example: Suppose the elevator cable breaks and the elevator falls. Imagine that an elevator travels from floor 1 20, feet to floor 10 30, feet and back to floor 1 20, feet without a noticeable stop at floor As the elevator accelerates towards floor 10, the passengers feel heavier than normal airplane climbing to 30, feet.
As the elevator approaches floor 10 and immediately changes direction to travel back towards floor 1, the passengers feel weightless free fall maneuver. Finally, as the elevator decelerates upon returning to floor 1, the passengers feel heavier than normal airplane descending to 20, feet.
So, the next time you feel your stomach drop on a Delta flight, smile and enjoy the ride! You just won a free second of weightlessness. Although a trip on the Vomit Comet does provide the sensation of weightlessness, it will not give you the name of astronaut. For that, you have to go to space!
Fortunately, Blue Origin and Virgin Galactic have catered their weightless experiences to those with slightly smaller checkbooks and slightly less ambitious space traveling plans. She studies the role of STAT transcription factors in cancer. A circular orbit around the Earth is easy to analyse in terms of weightlessness. What about an elliptical orbit? ISS is heavier so it tries to fall down however one more force is acting ,which acts tangent to it orbit. Here shapes of an orbit is largely dominated by velocity at which ISS is thrown at space, therefore in either case circular or ellipse downward force remains nullified.
And astronauts keep falling in their orbit. Thanks to indian muslim Scholar, Ahmad raza khan for his contribution to modern astronomy ,Science. You also need to explain why things fall toward the earth, and not any other direction. Furthermore, how does our atmosphere exist as a gradient, and why is water pressure stronger at the bottom of a container? Initially, the object would accelerate at a rate of about 9. Thank you. Is weightlessness only experienced when a body is in free fall?
What about when the body is floating? Can we experience weightlessness when we float? Well floating is not actually weightlessness but putting our mass surrounded by greater volume which intern makes us not feel that we are being lifted by volume instead of falling an suspended by mass.
Thank God for you smart guys out there. Your email address will not be published. Save my name, email, and website in this browser for the next time I comment. This is the source of weightlessness. If there was no force i.
To travel in a circular or elliptical path there must be a force and that force is your weight. In a Newtonian frame everything on the spacecraft including you are falling at the same rate of acceleration. Therefore the absence of differential accelerations means everything is weightless. This means that being on a reference frame that is falling or in an orbit is indistinguishable from being on a frame far removed from gravity fields, say in interstellar space or way out between galaxies.
This is the basis for the equivalence principle Einstein invoked to work general relativity. It is then for this reason the force of gravity in Newtonian mechanics is really a pseudo-force. Gravity is not really a force in a strict sense, but is due to the motion of paths in space or spacetime, where if that is curved the paths are extremal curves in the space.
This works for the capsule or the spatial extent of the frame very small. Gravity in the Newtonian perspective has a radial dependency, and a capsule with some spatial extent will then have a tidal acceleration on it.
In general relativity the tidal force is due to a portion of the Riemann curvature, but the Newtonian force of gravity is due to the connection terms that can be removed by coordinate choice. Looks like we are talking at cross-purposes. You are talking about a different reference frame the spacecraft. With Earth as the reference frame, the astronaut and the spacecraft are both accelerating at 9. In which case no matter where you are anywhere in the Universe you can never be weightless and the term becomes meaningless.
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