Why do astronauts on board ISS float around

When I was growing up it was centrifugal force that caused objects to move outwards. Like centrifugal clutches and the weights in a distributor would move outwards to advance the timing. Then I started reading that centrifugal force was not a real force at all it was really centripetal force. So, I thought I'd study this a little deeper. That is when I got on the subject of satellites in orbit. I read the following:

The motion of an orbiting satellite can be described by the same motion characteristics as any object in circular motion. The velocity of the satellite would be directed tangent to the circle at every point along its path. The acceleration of the satellite would be directed towards the center of the circle - towards the central body that it is orbiting. And this acceleration is caused by a net force that is directed inwards in the same direction as the acceleration. This centripetal force is supplied by gravity - the force that universally acts at a distance between any two objects that have mass. Were it not for this force, the satellite in motion would continue in motion at the same speed and in the same direction. It would follow its inertial, straight-line path. Like any projectile, gravity alone influences the satellite's trajectory such that it always falls below its straight-line, inertial path. They demonstrated this with the following image:


This picture shows an object following a path around the Earth at a precise distance above the Earth because inertia is causing the object to fly straight and gravity wants to pull the object down to Earth. What you have is a nice curve flight around the Earth. Well, if this is the case, then isn't this the same thing airplanes do. They fly around the Earth everyday. The airplane's engine is providing the inertia to cause the airplane to fly forward and gravity is trying to pull the airplane down. The pilot has to maintain altitude and direction and a nice curved path is maintained around the Earth just like a satellite does. It is really a balancing act between gravity and inertia. Gravity is trying to pull it down, but inertia keeps it from happening. If the airplane's engine stops, gravity will take over and it will free fall to the ground. If the satellite's inertia runs out, then the satellite will free fall to the ground. In this case, the only real difference between a satellite and an airplane is how high each fly. What I don't understand is why do all the videos show the astronauts floating around inside the ISS. To me that is no more possible than passengers on an airplane floating around inside the airplane. We all know that doesn't happen. Some say it is because the ISS is in free fall and it is like being on an free falling elevator. That can't be true because inertia is what keeps satellites and airplanes from free falling to the ground in the first place. Others say they float around because there is no gravity in space. That is not true, there is only 10% less gravity on the ISS then on Earth and that is not enough difference to keep passengers on an airplane from floating around. So, I sit here and wonder if the videos of the ISS true, false or I'm I totally off base on my reasoning?

Very interesting question, Yendor.

Much like, "why do people walking on the moon appear to be moving in slow motion?"

In reduced gravity, it is reasonable to think that they would actually move faster. But that's not what the "footage" shows. Maybe a believer can educate us?

Very interesting question, Yendor.

Much like, "why do people walking on the moon appear to be moving in slow motion?"

In reduced gravity, it is reasonable to think that they would actually move faster. But that's not what the "footage" shows. Maybe a believer can educate us?

Yes, I'm very interested in being educated on this.

This picture shows an object following a path around the Earth at a precise distance above the Earth because inertia is causing the object to fly straight and gravity wants to pull the object down to Earth. What you have is a nice curve flight around the Earth.

This depiction of "reality" is impossible.

Any drawing showing a circular orbit of an object around the Earth is bogus. Geostationary satellites are not only physically but also conceptually impossible.

In the vicinity of the Earth 3 main gravitational forces play a role (excluding the effects of our neighbors Mars and Venus, giant planets farther away and effects of the Milky Way).

Any object in space around the Earth must be susceptible (and thus the orbit of such an object is defined by that) to the gravitational fields/forces of:
- Earth
- Moon
- Sun

We know that the Earth and Moon are in an eternal tidal orbital dance with each other; the gravitational pull of the Earth at least works to the Moon (~380,000 km) and the center of gravity of this combined system is skewed. Even if a "geostationary" satellite were possible, it would orbit around that "point" (it's a path as Moon and Earth move in 3D) rather than around Earth.

Reciprocally our grand small sister gives us the effects of spring tides; it is able to lift half the water mass on the planet by meters and push it down by the same "pulling effect" (no physical term) on the antipodal side of Earth.

Then we have a huge Sun which is acting on this whole system as well.

To paint a circular orbit around Earth like the Earth-Moon gravitational field and the gravitational effects of the Sun do not exist is ridiculous science fiction showing a lack of understanding of the dynamic forces of space.

When I was growing up it was centrifugal force that caused objects to move outwards. Like centrifugal clutches and the weights in a distributor would move outwards to advance the timing. Then I started reading that centrifugal force was not a real force at all it was really centripetal force. So, I thought I'd study this a little deeper. That is when I got on the subject of satellites in orbit. I read the following:

Velocity, Acceleration and Force Vectors

The motion of an orbiting satellite can be described by the same motion characteristics as any object in circular motion. The velocity of the satellite would be directed tangent to the circle at every point along its path. The acceleration of the satellite would be directed towards the center of the circle - towards the central body that it is orbiting. And this acceleration is caused by a net force that is directed inwards in the same direction as the acceleration. This centripetal force is supplied by gravity - the force that universally acts at a distance between any two objects that have mass. Were it not for this force, the satellite in motion would continue in motion at the same speed and in the same direction. It would follow its inertial, straight-line path. Like any projectile, gravity alone influences the satellite's trajectory such that it always falls below its straight-line, inertial path. They demonstrated this with the following image:


This picture shows an object following a path around the Earth at a precise distance above the Earth because inertia is causing the object to fly straight and gravity wants to pull the object down to Earth. What you have is a nice curve flight around the Earth. Well, if this is the case, then isn't this the same thing airplanes do. They fly around the Earth everyday. The airplane's engine is providing the inertia to cause the airplane to fly forward and gravity is trying to pull the airplane down. The pilot has to maintain altitude and direction and a nice curved path is maintained around the Earth just like a satellite does. It is really a balancing act between gravity and inertia. Gravity is trying to pull it down, but inertia keeps it from happening. If the airplane's engine stops, gravity will take over and it will free fall to the ground. If the satellite's inertia runs out, then the satellite will free fall to the ground. In this case, the only real difference between a satellite and an airplane is how high each fly. What I don't understand is why do all the videos show the astronauts floating around inside the ISS. To me that is no more possible than passengers on an airplane floating around inside the airplane. We all know that doesn't happen. Some say it is because the ISS is in free fall and it is like being on an free falling elevator. That can't be true because inertia is what keeps satellites and airplanes from free falling to the ground in the first place. Others say they float around because there is no gravity in space. That is not true, there is only 10% less gravity on the ISS then on Earth and that is not enough difference to keep passengers on an airplane from floating around. So, I sit here and wonder if the videos of the ISS true, false or I'm I totally off base on my reasoning?

Inertia is not what keeps airplanes from falling.  Lift opposes gravity for an airplane.  And the difference between airplanes and satellites is not how high they fly, it is the speed.

Very interesting question, Yendor.

Much like, "why do people walking on the moon appear to be moving in slow motion?"

In reduced gravity, it is reasonable to think that they would actually move faster. But that's not what the "footage" shows. Maybe a believer can educate us?

You might move faster if the only difference was you had less weight to move around but you still have the full mass to move.  Then you have less friction with the ground so it is harder to get moving as well as stop.  The lower gravity makes them appear to move slower as they have more "hang time" vertically but if you watch their arms they still move at normal speeds.  Speeding up the footage makes their arms move way too fast.

When I was growing up it was centrifugal force that caused objects to move outwards. Like centrifugal clutches and the weights in a distributor would move outwards to advance the timing. Then I started reading that centrifugal force was not a real force at all it was really centripetal force. So, I thought I'd study this a little deeper. That is when I got on the subject of satellites in orbit. I read the following:

Velocity, Acceleration and Force Vectors

The motion of an orbiting satellite can be described by the same motion characteristics as any object in circular motion. The velocity of the satellite would be directed tangent to the circle at every point along its path. The acceleration of the satellite would be directed towards the center of the circle - towards the central body that it is orbiting. And this acceleration is caused by a net force that is directed inwards in the same direction as the acceleration. This centripetal force is supplied by gravity - the force that universally acts at a distance between any two objects that have mass. Were it not for this force, the satellite in motion would continue in motion at the same speed and in the same direction. It would follow its inertial, straight-line path. Like any projectile, gravity alone influences the satellite's trajectory such that it always falls below its straight-line, inertial path. They demonstrated this with the following image:


This picture shows an object following a path around the Earth at a precise distance above the Earth because inertia is causing the object to fly straight and gravity wants to pull the object down to Earth. What you have is a nice curve flight around the Earth. Well, if this is the case, then isn't this the same thing airplanes do.

No, it's not.

An airplane's forward motion is much too low for this to work. The dashed blue lines in the illustration would be far shorter for an airplane, but the green inward-pointing arrows would be the same size, so it wouldn't follow the red circular path; it would intercept the Earth.
 

They fly around the Earth everyday. The airplane's engine is providing the inertia to cause the airplane to fly forward and gravity is trying to pull the airplane down.

No, the engine is providing thrust, which is necessary to overcome drag from air resistance. The wings provide lift, which is necessary to overcome weight, which is due to gravity.

The pilot has to maintain altitude and direction and a nice curved path is maintained around the Earth just like a satellite does. It is really a balancing act between gravity and inertia. Gravity is trying to pull it down, but inertia keeps it from happening.

No, if thrust equals drag and lift equals weight, the airplane flies at a constant altitude and speed. More generally, the vector sum of thrust, drag, lift and weight determines whether the aircraft gains or loses altitude, speeds up or slows down; if they sum to zero, it has no altitude change and maintains speed.

If the airplane's engine stops, gravity will take over and it will free fall to the ground.

No, it will glide to the ground, which isn't free fall, because the wings provide some lift if they're moving forward. With the loss of thrust, drag will reduce speed, which reduces lift, so weight exceeds lift and the aircraft loses altitude.

If the satellite's inertia runs out, then the satellite will free fall to the ground.

Yes. But what would cause this?

As it is, because there is a very tenuous atmosphere even at the heights most satellites orbit, they do lose a little energy (and momentum) colliding with these particles, and their orbits do decay unless additional energy is supplied, usually in the form of a rocket engine in some form. This is a very slow process until the satellites get very low (for a satellite), however.

In this case, the only real difference between a satellite and an airplane is how high each fly.

Nope. They are completely different.

What I don't understand is why do all the videos show the astronauts floating around inside the ISS. To me that is no more possible than passengers on an airplane floating around inside the airplane. We all know that doesn't happen.

Not true... stay tuned.

Some say it is because the ISS is in free fall and it is like being on an free falling elevator.

They're right, too!

That can't be true because inertia is what keeps satellites and airplanes from free falling to the ground in the first place.

Satellites are in free-fall. Because their forward motion is high, the ground is falling away at the same rate, though. Airplanes stay aloft because of lift generated (mostly) by the wings, which causes drag, which must be overcome by thrust. They are not is free fall when flying normally.

--> An example of an airplane in free fall is the "Vomit Comet", whose passengers do float around inside the airplane

Others say they float around because there is no gravity in space. That is not true, there is only 10% less gravity on the ISS then on Earth and that is not enough difference to keep passengers on an airplane from floating around.

You are correct. Zero gravity is a misconception and does cause some confusion. Passengers in an orbiting spacecraft are in the same orbit as the spacecraft they're in, and both are in free fall, so there is nothing resisting the acceleration of gravity toward the center of the Earth, so they feel no weight. Gravity is very much in effect.

So, I sit here and wonder if the videos of the ISS true, false or I'm I totally off base on my reasoning?

The first and last are correct.

Quote from: Yendor on December 16, 2015, 01:05:18 PM

When I was growing up it was centrifugal force that caused objects to move outwards. Like centrifugal clutches and the weights in a distributor would move outwards to advance the timing. Then I started reading that centrifugal force was not a real force at all it was really centripetal force. So, I thought I'd study this a little deeper. That is when I got on the subject of satellites in orbit. I read the following:

Velocity, Acceleration and Force Vectors

The motion of an orbiting satellite can be described by the same motion characteristics as any object in circular motion. The velocity of the satellite would be directed tangent to the circle at every point along its path. The acceleration of the satellite would be directed towards the center of the circle - towards the central body that it is orbiting. And this acceleration is caused by a net force that is directed inwards in the same direction as the acceleration. This centripetal force is supplied by gravity - the force that universally acts at a distance between any two objects that have mass. Were it not for this force, the satellite in motion would continue in motion at the same speed and in the same direction. It would follow its inertial, straight-line path. Like any projectile, gravity alone influences the satellite's trajectory such that it always falls below its straight-line, inertial path. They demonstrated this with the following image:


This picture shows an object following a path around the Earth at a precise distance above the Earth because inertia is causing the object to fly straight and gravity wants to pull the object down to Earth. What you have is a nice curve flight around the Earth. Well, if this is the case, then isn't this the same thing airplanes do.

No, it's not.

An airplane's forward motion is much too low for this to work. The dashed blue lines in the illustration would be far shorter for an airplane, but the green inward-pointing arrows would be the same size, so it wouldn't follow the red circular path; it would intercept the Earth.
 

Quote

They fly around the Earth everyday. The airplane's engine is providing the inertia to cause the airplane to fly forward and gravity is trying to pull the airplane down.

No, the engine is providing thrust, which is necessary to overcome drag from air resistance. The wings provide lift, which is necessary to overcome weight, which is due to gravity.

Quote

The pilot has to maintain altitude and direction and a nice curved path is maintained around the Earth just like a satellite does. It is really a balancing act between gravity and inertia. Gravity is trying to pull it down, but inertia keeps it from happening.

No, if thrust equals drag and lift equals weight, the airplane flies at a constant altitude and speed. More generally, the vector sum of thrust, drag, lift and weight determines whether the aircraft gains or loses altitude, speeds up or slows down; if they sum to zero, it has no altitude change and maintains speed.

Quote

If the airplane's engine stops, gravity will take over and it will free fall to the ground.

No, it will glide to the ground, which isn't free fall, because the wings provide some lift if they're moving forward. With the loss of thrust, drag will reduce speed, which reduces lift, so weight exceeds lift and the aircraft loses altitude.

Quote

If the satellite's inertia runs out, then the satellite will free fall to the ground.

Yes. But what would cause this?

As it is, because there is a very tenuous atmosphere even at the heights most satellites orbit, they do lose a little energy (and momentum) colliding with these particles, and their orbits do decay unless additional energy is supplied, usually in the form of a rocket engine in some form. This is a very slow process until the satellites get very low (for a satellite), however.

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In this case, the only real difference between a satellite and an airplane is how high each fly.

Nope. They are completely different.

Quote

What I don't understand is why do all the videos show the astronauts floating around inside the ISS. To me that is no more possible than passengers on an airplane floating around inside the airplane. We all know that doesn't happen.

Not true... stay tuned.

Quote

Some say it is because the ISS is in free fall and it is like being on an free falling elevator.

They're right, too!

Quote

That can't be true because inertia is what keeps satellites and airplanes from free falling to the ground in the first place.

Satellites are in free-fall. Because their forward motion is high, the ground is falling away at the same rate, though. Airplanes stay aloft because of lift generated (mostly) by the wings, which causes drag, which must be overcome by thrust. They are not is free fall when flying normally.

--> An example of an airplane in free fall is the "Vomit Comet", whose passengers do float around inside the airplane

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Others say they float around because there is no gravity in space. That is not true, there is only 10% less gravity on the ISS then on Earth and that is not enough difference to keep passengers on an airplane from floating around.

You are correct. Zero gravity is a misconception and does cause some confusion. Passengers in an orbiting spacecraft are in the same orbit as the spacecraft they're in, and both are in free fall, so there is nothing resisting the acceleration of gravity toward the center of the Earth, so they feel no weight. Gravity is very much in effect.

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So, I sit here and wonder if the videos of the ISS true, false or I'm I totally off base on my reasoning?

The first and last are correct.

No, it's not.

An airplane's forward motion is much too low for this to work. The dashed blue lines in the illustration would be far shorter for an airplane, but the green inward-pointing arrows would be the same size, so it wouldn't follow the red circular path; it would intercept the Earth.

I would say the picture is just for providing an illustration. It is certainly not to scale. I've watched the ISS flight around the Earth and it makes a nice smooth curved path. 

No, the engine is providing thrust, which is necessary to overcome drag from air resistance. The wings provide lift, which is necessary to overcome weight, which is due to gravity.

You don't like it when I said the engine provides inertia? I can use thrust if you like. I understand that an airplane flies in the atmosphere and uses wings to give lift. However, The ISS has weight too and gravity is trying to pull it down also. I don't see much difference here between an airplane and the ISS. So this does not show why the astronauts float.

No, if thrust equals drag and lift equals weight, the airplane flies at a constant altitude and speed. More generally, the vector sum of thrust, drag, lift and weight determines whether the aircraft gains or loses altitude, speeds up or slows down; if they sum to zero, it has no altitude change and maintains speed.

How is this different for the ISS. I don't see your point. How does this cause the Astronauts to float around?

No, it will glide to the ground, which isn't free fall, because the wings provide some lift if they're moving forward. With the loss of thrust, drag will reduce speed, which reduces lift, so weight exceeds lift and the aircraft loses altitude.

I believe that a large plane will glide a little if the engines fail, but they will take a nose dive directly to the ground. I don't see why this causes Astronauts to float.

Yes. But what would cause this?

As it is, because there is a very tenuous atmosphere even at the heights most satellites orbit, they do lose a little energy (and momentum) colliding with these particles, and their orbits do decay unless additional energy is supplied, usually in the form of a rocket engine in some form. This is a very slow process until the satellites get very low (for a satellite), however.

I realize all this. I still don't see why Astronauts float.

Nope. They are completely different.

When I said the only real difference between an airplane and a satellite was how high they fly, I meant that one flies in the atmosphere and one flies in no atmosphere and because of this there would be physical differences between them. I guess I didn't explain that well enough.

Not true... stay tuned.

I'm staying tuned.

They're right, too!

I don't believe so. Inertia keeps it from happening.

Satellites are in free-fall. Because their forward motion is high, the ground is falling away at the same rate, though. Airplanes stay aloft because of lift generated (mostly) by the wings, which causes drag, which must be overcome by thrust. They are not is free fall when flying normally.

--> An example of an airplane in free fall is the "Vomit Comet", whose passengers do float around inside the airplane

You say that satellites are in freefall because their forward motion is high and the ground is actually falling away from them at the same rate. If that is the case then there should be less gravity caused by centripetal force and the straight-line path due to the high rate of inertia should cause the object to go flying away from Earth and not curve around it. Like I said before, airplanes do not fly in outer space so they do need an engine and wings to fly and maintain the inertia to keep them flying around the Earth the same way the ISS does. Granted, the "Vomit Comet" does cause the passengers to float around because the plane is heading straight towards the ground at a high rate of speed and the passenger do float around. So would the Astronauts float around if the ISS was heading straight towards the ground.  However, that is not the normal way an airplane or the ISS flies around the Earth. Watch some videos of the ISS in flight, they follow the Earth's curvature perfectly because of Inertia or thrust and wings in the airplanes case, in order to keep gravity or whatever it is from pulling them to the ground. There has to be a better answer as to why Astronauts float around.

Quote from: Yendor on December 16, 2015, 01:05:18 PM

This picture shows an object following a path around the Earth at a precise distance above the Earth because inertia is causing the object to fly straight and gravity wants to pull the object down to Earth. What you have is a nice curve flight around the Earth.

This depiction of "reality" is impossible.
Any drawing showing a circular orbit of an object around the Earth is bogus. Geostationary satellites are not only physically but also conceptually impossible.
In the vicinity of the Earth 3 main gravitational forces play a role (excluding the effects of our neighbors Mars and Venus, giant planets farther away and effects of the Milky Way).
Any object in space around the Earth must be susceptible (and thus the orbit of such an object is defined by that) to the gravitational fields/forces of:
- Earth
- Moon
- Sun

Loosely speaking what you say has some validity, at least it is something to be considered in looking at the orbits of not only satellites, but the moon itself.  What makes it harder to grasp initially is that the sun's gravitational field at the moon is greater than that of the earth, so it is hard to see why the moon orbits the earth and not the sun. 
Certainly we know the moon does orbit the earth, then the earth-moon combination orbits the sun.  The calculations a way beyond me, but a so-called "Hills Sphere" around the earth can be defined where a satellite (such as the moon) will orbit the earth and not be trapped by the sun.  You can read up on it in https://van.physics.illinois.edu/qa/listing.php?id=18501.

For artificial satellites orbiting the earth there is less of a problem because:
1) they are much closer to the earth than to the moon,
2) the mass of the moon is only about 1.2% the mass of the earth.
Since the gravitational field the satellite is subject to depends on m/d^2 the moon has much less effect even for geostationary orbits.
Nevertheless it is a matter that has been analysed in detail way back before 1961.  You can read up in: Luni-Solar  Perturbations of the Orbit of an Earth Satellite G. E. Cook, The Geophysical Journal of the ROYAL ASTRONOMICAL SOCIETY Vol. 6 No. 3 April 1962.  see http://gji.oxfordjournals.org/content/6/3/271.full.pdf
 

We know that the Earth and Moon are in an eternal tidal orbital dance with each other; the gravitational pull of the Earth at least works to the Moon (~380,000 km) and the center of gravity of this combined system is skewed. Even if a "geostationary" satellite were possible, it would orbit around that "point" (it's a path as Moon and Earth move in 3D) rather than around Earth.

If when you say "orbit around that point" you mean the satellite orbits the barycentre of the earth-moon combination, no that is not true any more than the moon orbiting the barycentre of the earth-sun combination - that would be inside or very near the sun.
A "geostationary satellite" is certainly possible, there are numerous ones in orbit.  The moon's gravitational field will have some effect, but because of the inverse square law and the moon's mass being so must less the effect is small.  Orbital corrections for these satellites are done, and when they run aout of fuel for this task their service life quickly ends.

Reciprocally our grand small sister gives us the effects of spring tides; it is able to lift half the water mass on the planet by meters and push it down by the same "pulling effect" (no physical term) on the antipodal side of Earth.

Yes, the moon (and sun) do control our tides, but do not so much bodily lift the oceans as cause the ocean water to move towards where the moon-sun combination has the greatest effect.  The second tide (when the moon is on the opposite side) happens because the gravitational effect of the moon-sun is least there, so the rotation of the earth causes the bulge on that side.
Hence:
1) the time of high or low tide lags the moon and is also greatly affected but the local ocean floor profile, so much so that some places get extreme tides (Bay of Fundy), and some places get almost no tide (parts of Western Australian Coast).
2) small bodies of water do not experience significant tides, even the Mediterranean Sea has tides of only a few centimetres.

Then we have a huge Sun which is acting on this whole system as well.
To paint a circular orbit around Earth like the Earth-Moon gravitational field and the gravitational effects of the Sun do not exist is ridiculous science fiction showing a lack of understanding of the dynamic forces of space.

While the whole system is certainly extremely complicated, luckily the effects of bodies other than the earth on artificial satellites of earth is quite small - maybe more by good luck that good management.  The sun, other planets and especially the other stars have no significant effect till we get much further from earth that geostationary satellites.

Maybe you'll call this a load of rubbish, but whatever there it is!
E&OE as they say.

Yendor, the ISS is falling.  The people inside are falling with it.  It's lateral velocity means it continually misses the planet. 

I don't know what is so hard to understand about all this.  Do you think the astronauts should be held to the 'floor' of the ISS or held to the 'ceiling' if they can't possibly 'float' (as you say)?

See here for context.

No, it's not.

An airplane's forward motion is much too low for this to work. The dashed blue lines in the illustration would be far shorter for an airplane, but the green inward-pointing arrows would be the same size, so it wouldn't follow the red circular path; it would intercept the Earth.

I would say the picture is just for providing an illustration. It is certainly not to scale.

It can still be used as a basis to compare different flight paths, though. Do you not understand what it's illustrating?

I've watched the ISS flight around the Earth and it makes a nice smooth curved path. 

Yes, it does. Orbits are smooth curves. So?

No, the engine is providing thrust, which is necessary to overcome drag from air resistance. The wings provide lift, which is necessary to overcome weight, which is due to gravity.

You don't like it when I said the engine provides inertia? I can use thrust if you like.

Do you think inertia and thrust are interchangeable? Really? They're not.

No wonder you have difficulty understanding this.

I understand that an airplane flies in the atmosphere and uses wings to give lift. However, The ISS has weight too

No, it has mass but no weight because it's in free fall.

and gravity is trying to pull it down also.

That's the centripetal acceleration you keep bringing up. It exactly matches the rate of increase in distance from the center of the Earth a straight line path would have at all times in a circular orbit.

I don't see much difference here between an airplane and the ISS.

Since you're confusing inertia with thrust, and a very muddled idea how things work in reality, this is not surprising.

So this does not show why the astronauts float.

Your not understanding the difference between an airplane and the ISS is why you don't understand why the astronauts float within (and near) the ISS. Airplanes in level flight are not in free fall. The ISS is (almost) always in free fall. So is everything inside it.

No, if thrust equals drag and lift equals weight, the airplane flies at a constant altitude and speed. More generally, the vector sum of thrust, drag, lift and weight determines whether the aircraft gains or loses altitude, speeds up or slows down; if they sum to zero, it has no altitude change and maintains speed.

How is this different for the ISS.

Airplanes flying in the atmosphere require thrust to overcome atmospheric drag, and require lift to compensate for weight because a free-fall trajectory would intercept the Earth. The ISS, and all satellites in stable orbits, have no atmospheric drag, so they require no thrust, and have no weight, even though they have mass, because they are in free fall, so they don't need lift. Needing thrust and lift to overcome drag and weight is different from not needing thrust and lift because there is no drag and weight. That's how they're different.

I don't see your point. How does this cause the Astronauts to float around?

Both the astronauts and the spacecraft they're in are in the same orbit, so they follow the same path through space, so their relative motions are zero.

No, it will glide to the ground, which isn't free fall, because the wings provide some lift if they're moving forward. With the loss of thrust, drag will reduce speed, which reduces lift, so weight exceeds lift and the aircraft loses altitude.

I believe that a large plane will glide a little if the engines fail,

Yes, they will glide some because as long as there is forward airspeed the wings will produce some lift. The glide ratio of a Boeing 747-200 is 15:1; that is, it can travel 15 km horizontally for each 1 km of altitude it loses.

but they will take a nose dive directly to the ground.

This doesn't necessarily follow. Look up British Airway Flight 9 to see the particulars of the record for the longest glide of a non-purpose-built aircraft that stood for years.  Since FE enthusiasts seem to like youtube videos, here's a 45-minute-long, but entertaining, documentary about it: " class="bbc_link" target="_blank" rel="noopener noreferrer">

Of course, there's even a list of long glides in airliners.

So, no... complete engine failure doesn't necessarily mean a nose dive directly to ground.

I don't see why this causes Astronauts to float.

Astronauts floating in the ISS aren't aboard airplanes. The ISS is different from an airplane. That's not hard to see.

Yes. But what would cause this?

As it is, because there is a very tenuous atmosphere even at the heights most satellites orbit, they do lose a little energy (and momentum) colliding with these particles, and their orbits do decay unless additional energy is supplied, usually in the form of a rocket engine in some form. This is a very slow process until the satellites get very low (for a satellite), however.

I realize all this. I still don't see why Astronauts float.

Yes, you've made that plain. Either you're lying about not seeing why astronauts float, you're very slow on the uptake, or you're trying really, really hard not to understand. You probably know which of these is right. Which one is it?

Nope. They are completely different.

When I said the only real difference between an airplane and a satellite was how high they fly, I meant that one flies in the atmosphere and one flies in no atmosphere and because of this there would be physical differences between them. I guess I didn't explain that well enough.

OK. When you say the only real difference is the altitude, you didn't mean that. Got it.

Not true... stay tuned.

I'm staying tuned.

They're right, too!

I don't believe so. Inertia keeps it from happening.

If "inertia" is the same as "thrust and lift" to you, then, yeah. But it's not, really. I can see why this is hard for you to understand.

Satellites are in free-fall. Because their forward motion is high, the ground is falling away at the same rate, though. Airplanes stay aloft because of lift generated (mostly) by the wings, which causes drag, which must be overcome by thrust. They are not is free fall when flying normally.

--> An example of an airplane in free fall is the "Vomit Comet", whose passengers do float around inside the airplane

You say that satellites are in freefall because their forward motion is high and the ground is actually falling away from them at the same rate. If that is the case then there should be less gravity caused by centripetal force and the straight-line path due to the high rate of inertia [inertia isn't a rate; I think you mean speed] should cause the object to go flying away from Earth and not curve around it. Like I said before, airplanes do not fly in outer space so they do need an engine and wings to fly and maintain the inertia speedto keep them flying around the Earth the same way the ISS does[going around the Earth is about the only thing they might have in common]. Granted, the "Vomit Comet" does cause the passengers to float around because the plane is heading straight towards the ground at a high rate of speed and the passenger do float around[they're not going "straight towards the ground", they follow a flight path that mimics a ballistic curve]. So would the Astronauts float around if the ISS was heading straight towards the ground. 

If that was a ballistic trajectory, yes.

However, that is not the normal way an airplane or the ISS flies around the Earth [not normal (but, obviously possible) for an airplane, normal for the ISS]. Watch some videos of the ISS in flight, they follow the Earth's curvature perfectly because of Inertia or thrust and wings in the airplanes case, in order to keep gravity or whatever it is from pulling them to the ground.

Inertia or thrust and wings? What?

There has to be a better answer as to why Astronauts float around.

Nope. Both the astronauts and the spacecraft they're in are in the same orbit, so they follow the same path through space, so their relative motions are zero. They're both in free fall. What's wrong with that answer? "I don't like it" is not an explanation. Nor is "I don't understand it.

If the so called ISS is orbiting or falling around the Earth like we are told then something must be acting on it to push it away as the so called gravity of Earth tries to pull it down.

Now if it's the speed of the ISS that keeps it up it must require something more than gravity. Why?

Well, if we are told that an aeroplane stays up high by going fast around Earth's supposed ball shape and it also uses the atmosphere to give it lift to keep it orbiting against the so called pull of gravity, then surely your space should have something more for the ISS.
Any ideas?

If the so called ISS is orbiting or falling around the Earth like we are told then something must be acting on it to push it away as the so called gravity of Earth tries to pull it down.

Now if it's the speed of the ISS that keeps it up it must require something more than gravity. Why?

Well, if we are told that an aeroplane stays up high by going fast around Earth's supposed ball shape and it also uses the atmosphere to give it lift to keep it orbiting against the so called pull of gravity, then surely your space should have something more for the ISS.
Any ideas?

The ISS simply has enough lateral motion that the ground falls away aat the same rate as the ISS falls towards the earth. The result is that the same altitude (ish) is maintained.

Aircraft have to create lift using aerofoils and the atmosphere to balance against gravity. This typically requires thrust from engines or in the case of gliders thermal up draughts.

If the so called ISS is orbiting or falling around the Earth like we are told then something must be acting on it to push it away as the so called gravity of Earth tries to pull it down.

Now if it's the speed of the ISS that keeps it up it must require something more than gravity. Why?

Well, if we are told that an aeroplane stays up high by going fast around Earth's supposed ball shape and it also uses the atmosphere to give it lift to keep it orbiting against the so called pull of gravity, then surely your space should have something more for the ISS.
Any ideas?

Imagine you are moving forward at constant speed. A constant force appears on you in direction from your left to your right (always perpendicular to your forward movement). What will happen? You will start moving in curved lines, circles as special case.

Maybe you'll call this a load of rubbish, but whatever there it is!
E&OE as they say.

Thank you for this extensive post. This is the level of thinking I was looking for.

Unfortunately both the post and the page you link to (it starts off well, the lower part with the Langrangian "points" is fantasy) is a mix of science and NASA Disney "science".

I will address the points trying to unravel the mysteries.

Loosely speaking what you say has some validity, at least it is something to be considered in looking at the orbits of not only satellites, but the moon itself.  What makes it harder to grasp initially is that the sun's gravitational field at the moon is greater than that of the earth, so it is hard to see why the moon orbits the earth and not the sun. 
Certainly we know the moon does orbit the earth, then the earth-moon combination orbits the sun.  The calculations a way beyond me, but a so-called "Hills Sphere" around the earth can be defined where a satellite (such as the moon) will orbit the earth and not be trapped by the sun.  You can read up on it in https://van.physics.illinois.edu/qa/listing.php?id=18501.

I see what is meant here and the "change of the field" is the defining factor and not the field itself. That makes sense.

The gravitational field of our central celestial body, the Sun, even extends all the way to the Oort cloud @ ~2000-5000 AU, some may say even 50,000 AU (0.79 ly). This Oort cloud is theoretical; it is postulated, so we don't know if it really exists. But if it does, it means the gravitational field of the Sun is amazingly large.

If we disregard the Oort cloud as being too theoretical, empirical science is my basis, not theoretical, then the Kuiper belt becomes the outermost sphere of influence of the Sun's gravitational force, at around 50 AU let's say to have a nice round number. Not too much more than Pluto (with its highly elliptical orbit; 30-49 AU).

For artificial satellites orbiting the earth ...

So this "information" I don't use. I stick to science and try to avoid these fantasies about "artificial satellites orbiting the Earth".
 

If when you say "orbit around that point" you mean the satellite orbits the barycentre of the earth-moon combination, no that is not true any more than the moon orbiting the barycentre of the earth-sun combination - that would be inside or very near the sun.

This is a good point, but why can the Earth-Moon system not orbit the barycentre of the Sun? You separate the Moon now from the Earth-Moon system, but it's a combined system; you cannot separate Earth and Moon as they are in such a strong gravitational dance.

The Earth's Moon is not pulled into the Sun just like the moons of other planets are not pulled into the Sun. Their stable orbits (by definition; gravitational equilibrium) are functioning for billions of years. So while the gravitational field of the Sun is strong and may act strong on Moons, it still is the gravitational field of the planet they orbit that defines the orbit; otherwise there wouldn't be moons at all; all would be pulled into the Sun.

Also, if the Sun would attract everything else, there would be no meteorites (on Earth, Moon or Mercury) yet we have extensive proof they do exist and crash into celestial bodies, up to the present (Arizona and the daily meteorites reaching Earth's surface).

Orbital corrections for these satellites are done, and when they run aout of fuel for this task their service life quickly ends.

Yes, this is complete fantasy, not science. "Orbital corrections", corrections from what exactly? Fuel is useless in space.

Yes, the moon (and sun) do control our tides, but do not so much bodily lift the oceans as cause the ocean water to move towards where the moon-sun combination has the greatest effect.  The second tide (when the moon is on the opposite side) happens because the gravitational effect of the moon-sun is least there, so the rotation of the earth causes the bulge on that side.
Hence:
1) the time of high or low tide lags the moon and is also greatly affected but the local ocean floor profile, so much so that some places get extreme tides (Bay of Fundy), and some places get almost no tide (parts of Western Australian Coast).
2) small bodies of water do not experience significant tides, even the Mediterranean Sea has tides of only a few centimetres.

Ok, the effect of the tidal force of the Moon can be observed differently and indeed the geometry of the basin is much more important for tide than the force of the Moon as normal tides in the Mediterranean are insignificant, rightly pointed out by you.

Still that doesn't dispute the fact that the gravity of Sun and Moon do act on Earth. Quantifying all this is virtually impossible, but we observe the effects and you've described the process in enough detail for everybody to understand, thanks again.

While the whole system is certainly extremely complicated, luckily the effects of bodies other than the earth on artificial satellites of earth is quite small - maybe more by good luck that good management.

That is a claim "quite small" and an explanation for the claim "maybe good luck". It is however based on the premise that artificial satellites would work, something which is not the case as artificial satellites cannot exist in the first place.

The sun, other planets and especially the other stars have no significant effect till we get much further from earth that geostationary satellites.

Also this would be impossible. The Sun definitely works within the Earths SOI as shown by the tidal forces. Again, it is based on a false premise.

E&OE as they say.

Enjoy & over enjoy? I don't know this abbreviation.

Thanks for the post; definitely one of the best reactions I've seen so far.

gaia... since u seem to know soo well orbital mechanics can u provide some scientific paper or mathematical/physics evidence of your claims on rocket propulsion and orbits?

Yendor, the ISS is falling.  The people inside are falling with it.  It's lateral velocity means it continually misses the planet. 

I don't know what is so hard to understand about all this.  Do you think the astronauts should be held to the 'floor' of the ISS or held to the 'ceiling' if they can't possibly 'float' (as you say)?

silhouette, I know you mean well, but I've heard the same thing as you 1000 times, 'the ISS is free falling around the Earth and that is why the astronauts are floating'. I do take issue with you when you say demeaning things like, "I don't know what is so hard to understand about all this." Do you think I can't comprehend the meaning of that and you are trying to explain it to me in a simpler way? My point to this is, as I stated right off the bat, satellites and the ISS can't be in freefall because of lateral movement caused by the inertia of the orbiting unit. If in fact the objects that are orbiting the Earth lose their inertia, then they would freefall back to Earth. Now, my question to you is, I don't know what is so hard to understand about all this?

The ISS simply has enough lateral motion that the ground falls away aat the same rate as the ISS falls towards the earth.

This is why you lot really shouldn't try to explain things in a simple manner.

Because it always shows what complete garbage you are pushing.

Stick to spamming 'science-like language' & authoritative-looking equations in future.

Plus: LOL!!!

To me, the notion that orbiting satellites or the ISS are in free fall back to Earth but keeps missing it is ridiculous. People are also floating around because of it. What happened to gravity pulling things to the center of the Earth. This whole notion makes it sound like gravity pulls things towards the side of the Earth. The definition of free fall alone should be enough to convince someone this is wrong.

 free fall
noun
1.
downward movement under the force of gravity only.
"the path of a body in free fall"
verb
1.
move under the force of gravity only; fall rapidly.

Free fall is the downward movement under the force of gravity only. the key here is 'gravity only'. The satellite is not under the influence of the force of gravity alone. If flying objects were, then yes they would probably free fall back to Earth and not miss it. The force of Inertia is also in play here. Inertia is what keeps the satellite's velocity going strong. We use the word inertia because the satellites and the ISS are claimed to be in a vacuum, free from atmospheric resistance. If we are talking airplanes then we use the word thrust because they fly in the atmosphere and there is atmospheric resistance. The velocity is what keeps gravity from pulling flying objects to the ground. If velocity is not enough then flying objects will fall to the ground. Unless it is a blimp or a hot air or helium filled balloon.

The article at this website http://worldnpa.org/abstracts/abstracts_6546.pdf touches on my meaning a little. I do think there would be no floating around of people though.

To me, the notion that orbiting satellites or the ISS are in free fall back to Earth but keeps missing it is ridiculous. People are also floating around because of it. What happened to gravity pulling things to the center of the Earth. This whole notion makes it sound like gravity pulls things towards the side of the Earth. The definition of free fall alone should be enough to convince someone this is wrong.

Yes, it convinces me that you don't understand the concept of vector components.

To me, the notion that orbiting satellites or the ISS are in free fall back to Earth but keeps missing it is ridiculous.

Statements like this are why people like silhouette and me wonder why it's so hard for you to grasp the concept of free fall.

People are also floating around because of it. What happened to gravity pulling things to the center of the Earth. This whole notion makes it sound like gravity pulls things towards the side of the Earth. The definition of free fall alone should be enough to convince someone this is wrong.

 free fall
noun
1.
downward movement under the force of gravity only.
"the path of a body in free fall"
verb
1.
move under the force of gravity only; fall rapidly.

Note the term "force" in that definition. Gravity is the only force involved in Keplerian orbits. The horizontal component doesn't require any force to maintain.

Free fall is the downward movement under the force of gravity only. the key here is 'gravity only'.

Gravity is the only thing exerting downward (or upward) force. This is completely consistent with the definitions above.

The satellite is not under the influence of the force of gravity alone.

What are the other forces acting on it?

If flying objects were, then yes they would probably free fall back to Earth and not miss it. The force of Inertia is also in play here. Inertia is what keeps the satellite's velocity going strong.

Inertia keeps a mass moving in a straight line at a constant speed (i.e. keeps it moving at a constant velocity - that's what inertia does). A force is necessary to cause it to change velocity. The force of gravity causes a satellite in a circular orbit to change direction, but not speed.

We use the word inertia because the satellites and the ISS are claimed to be in a vacuum, free from atmospheric resistance.

You use the word inertia when you mean velocity, probably because you don't understand what you are talking about.

If we are talking airplanes then we use the word thrust because they fly in the atmosphere and there is atmospheric resistance. The velocity is what keeps gravity from pulling flying objects to the ground. If velocity is not enough then flying objects will fall to the ground. Unless it is a blimp or a hot air or helium filled balloon.

No, lift is what keeps these things from falling to the ground. Lift for an airfoil (like an airplane wing) is a function of air speed; if the air speed is too low, there is not enough lift to overcome the airplane's weight, and it loses altitude. Lift for aerostats (lighter-than-air craft) is due to buoyancy, and is not dependent on air speed.

The article at this website http://worldnpa.org/abstracts/abstracts_6546.pdf touches on my meaning a little. I do think there would be no floating around of people though.

That's a nice paper. Thanks for the reference! It nicely puts to rest the argument for UA as a substitute for gravity. Thanks, again!! Link saved.

Did you read it? Did you understand what it is saying? The fact that you cite it here along with that comment suggests you don't have a clue what it means. Can you describe, in your own words, what the section titled "Is an Orbiting Satellite in Free Fall?" is saying? How large is the described effect in a body the size of the ISS?

[Edit] Typo and formatting.

The article at this website http://worldnpa.org/abstracts/abstracts_6546.pdf touches on my meaning a little. I do think there would be no floating around of people though.

That is really a very telling article and should be read before anyone criticises too severely what I put here.

In its simplest from the FET uses the Equivalence Principle to replace the gravitational field observed on the earth's surface.  I contend that this is not a valid application of the Equivalence Principle.

we [...] assume the complete physical equivalence of a gravitational field and a corresponding acceleration of the reference system.
— Einstein, 1907

This very brief statement of Einstein needs a little qualification.  If the reference system under consideration is not small enough for the gravitational field to be considered constant over its range then there can be no complete physical equivalence.

This is stressed in the fuller presentation of the Equivalence Principle.

Importance of the Equivalence Principle

An equivalent formulation of the Principle of Equivalence is that at any local (that is, sufficiently small) region in spacetime it is possible to formulate the equations governing physical laws such that the effect of gravitation can be neglected. This in turn means that the Special Theory of Relativity is valid for that particular situation, and this in turn allows a number of things to be deduced because the solution of the equations for the Special Theory of Relativity is beyond the scope of our course, but is not particularly difficult for those trained in the required mathematics.  from http://csep10.phys.utk.edu/astr162/lect/cosmology/equivalence.html

In the case of the earth we can readily measure variations in the gravitational field.  The most obvious is due to altitude, but there are more subtle variations due to the presence of ore bodies as used in gravimetric surveys for minerals.
If the earth is spherical there is also the variation in direction as we move over the earths surface.  In the context of a globe earth ~ flat earth discussion this is harder to "pin down" as it involves measuring small angular differences over large distances, so I will leave it out of the discussion.

As a result this the concept of Universal Acceleration can replace a gravitational field only if the reference system (the whole earth) is sufficiently small for the gravitational field to be considered constant over the whole system.

This is clearly not satisfied, so the concept of Universal Acceleration cannot be be used to replace the gravitational field.
 and shows quite clearly that UA is simply an invalid substitute for the observe "gravitational field".

Even if a "geostationary" satellite were possible, it would orbit around that "point" (it's a path as Moon and Earth move in 3D) rather than around Earth.

I know I'm late but I just have to point this out. The center of mass of the Earth-Moon system is actually inside the Earth.

I know I'm late but I just have to point this out. The center of mass of the Earth-Moon system is actually inside the Earth.

Welcome, yes, that has been shown with a simple animation already here. So a "geostationary orbit", even if that were technically possible, would be an orbit around that center of mass inside the Earth and will never produce a circular geostationary orbit whose center of mass is the exact core of the Earth.

Quote from: Mainframes on December 18, 2015, 05:38:33 AM

The ISS simply has enough lateral motion that the ground falls away aat the same rate as the ISS falls towards the earth.

This is why you lot really shouldn't try to explain things in a simple manner.

Because it always shows what complete garbage you are pushing.

Stick to spamming 'science-like language' & authoritative-looking equations in future.

Plus: LOL!!!

Alright Papa, here's an example that might clear things up. When a ball hangs by a string, the string is acting on the ball with an upward force. This force is called tension. Imagine the ball being swung in a circle (let's say it's on a frictionless table just to rule out any vertical forces). The ball is being pulled towards the center of the circle by the tension from the string. Side note: you can calculate exactly how strong this force is with the formula F = mv²/r where F is the tension force in Newtons, m is the mass of the ball in kilograms, v is speed of the ball in meters per second, and r is the length of the string in meters. So, if the ball is constantly being pulled towards the center, why doesn't it ever reach the center? Simply put, the ball is moving fast enough to "miss" the center. This is what people mean when they say objects in orbit "miss" the ground.

Quote from: Yendor on December 18, 2015, 01:16:55 PM

To me, the notion that orbiting satellites or the ISS are in free fall back to Earth but keeps missing it is ridiculous.

Statements like this are why people like silhouette and me wonder why it's so hard for you to grasp the concept of free fall.

Quote

People are also floating around because of it. What happened to gravity pulling things to the center of the Earth. This whole notion makes it sound like gravity pulls things towards the side of the Earth. The definition of free fall alone should be enough to convince someone this is wrong.

 free fall
noun
1.
downward movement under the force of gravity only.
"the path of a body in free fall"
verb
1.
move under the force of gravity only; fall rapidly.

Note the term "force" in that definition. Gravity is the only force involved in Keplerian orbits. The horizontal component doesn't require any force to maintain.

Quote

Free fall is the downward movement under the force of gravity only. the key here is 'gravity only'.

Gravity is the only thing exerting downward (or upward) force. This is completely consistent with the definitions above.

Quote

The satellite is not under the influence of the force of gravity alone.

What are the other forces acting on it?

Quote

If flying objects were, then yes they would probably free fall back to Earth and not miss it. The force of Inertia is also in play here. Inertia is what keeps the satellite's velocity going strong.

Inertia keeps a mass moving in a straight line at a constant speed (i.e. keeps it moving at a constant velocity - that's what inertia does). A force is necessary to cause it to change velocity. The force of gravity causes a satellite in a circular orbit to change direction, but not speed.

Quote

We use the word inertia because the satellites and the ISS are claimed to be in a vacuum, free from atmospheric resistance.

You use the word inertia when you mean velocity, probably because you don't understand what you are talking about.

Quote

If we are talking airplanes then we use the word thrust because they fly in the atmosphere and there is atmospheric resistance. The velocity is what keeps gravity from pulling flying objects to the ground. If velocity is not enough then flying objects will fall to the ground. Unless it is a blimp or a hot air or helium filled balloon.

No, lift is what keeps these things from falling to the ground. Lift for an airfoil (like an airplane wing) is a function of air speed; if the air speed is too low, there is not enough lift to overcome the airplane's weight, and it loses altitude. Lift for aerostats (lighter-than-air craft) is due to buoyancy, and is not dependent on air speed.

Quote

The article at this website http://worldnpa.org/abstracts/abstracts_6546.pdf touches on my meaning a little. I do think there would be no floating around of people though.

That's a nice paper. Thanks for the reference! It nicely puts to rest the argument for UA as a substitute for gravity. Thanks, again!! Link saved.

Did you read it? Did you understand what it is saying? The fact that you cite it here along with that comment suggests you don't have a clue what it means. Can you describe, in your own words, what the section titled "Is an Orbiting Satellite in Free Fall?" is saying? How large is the described effect in a body the size of the ISS?

[Edit] Typo and formatting.

Back to you again alpha,
I enjoy this debate, but I do want to keep it civil. Let's not get into a pissing contest over this matter. I don't claim to have learned everything about science and you will catch me saying things that doesn't coincide with what you were taught. That doesn't mean you have to call me out about it and make me look foolish. Let's start again with a clean slate on this matter and see if we can find some common ground. The subject of this thread is, "Why do astronauts on board ISS float around?". My thoughts are this, I've always heard that satellites stay in orbit because they free fall around the Earth and that is why astronauts float around inside the ISS. I pondered this notion and wondered why they say this because it really made little sense to me. I thought about airplanes, they don't fall around the Earth and the passengers don't float around. So I wondered what is the differences between a satellite and an airplane. They both fly around the Earth. So this is what I came up with.

1. A satellite is launched into orbit and it flies around the Earth.
2. An airplane flies off the runway and it too flies around the Earth.
3. Without getting on another subject, Let's say gravity tries to pull both satellites and airplanes back down to Earth.
4. Inertia keeps the satellite and an airplane from allowing gravity to pull them both back down to Earth.

It just seems to me that if an airplane could fly outside Earth's atmosphere, it would act no different then it does flying inside Earth's atmosphere.

Now, please go to the below NASA website and read what it says about satellites.
Take note it says,"When these two forces are equal, the ball remains in orbit", meaning gravity and inertia. (You had mentioned before that gravity was the only force acting upon a satellite.)

http://www.gma.org/surfing/satellites/inorbit.html 

My thoughts are this, If these two forces, gravity and inertia are acting on an airplane and a satellite to keep them both flying around the Earth, then when does this free fall come into play? Notice too that the article does say, "A satellite's forward motion is controlled by rockets. When the rockets are not fired, inertia keeps the satellite going in one direction." So, rockets provide the inertia for satellites and a jet engine provides the inertia for airplanes. I realize that the rockets are probably not used that much because a satellite is flying in a vacuum with little resistance. However, it does clearly say inertia is required for a satellite to fly around the Earth. The only way, that I can see a satellite in free fall is if inertia gives out and then gravity can pull it back down to Earth. This too will happen with an airplane. Lets not get into, well a plane will glide because of its wings and some planes will glide longer than others. That is just meaningless and does nothing but try and change the subject. So alpha, without getting all pissed off, please explain to me, as simple as possible, in your own words, without math and not saying so and so said it works this way, why my thoughts are all wrong.

1. A satellite is launched into orbit and it flies around the Earth.

at an average speed of 17,000mph.

2. An airplane flies off the runway and it too flies around the Earth.

at an average speed of 100-200mph.  Airliners cruise at 500-600mph.

3. Without getting on another subject, Let's say gravity tries to pull both satellites and airplanes back down to Earth.
4. Inertia keeps the satellite and an airplane from allowing gravity to pull them both back down to Earth.

Inertia keeps the satellite moving at that high-rate of speed while gravity pulls it toward Earth.  It continually misses, and there is almost nothing to slow it.

Inertia will let the airplane glide for a bit before dropping.  Without the constant thrust from the propeller, etc, wind resistance would slow it quickly.  Lift generated by the wings is what keeps it flying. 

It just seems to me that if an airplane could fly outside Earth's atmosphere, it would act no different then it does flying inside Earth's atmosphere.

At it's same atmospheric speed, it would drop quickly as there would be no air for the wings to provide lift.

 

The only way, that I can see a satellite in free fall is if inertia gives out and then gravity can pull it back down to Earth.

It is in free-fall.  Inertia keeps it moving sideways fast enough that is keeps missing the planet.  Thrust brought it up to that speed (or is used occasionally to keep it at that speed)

This too will happen with an airplane.

In the atmosphere, yes.  It will lose it's speed, which is required in addition to air for the wings to provide lift.  Outside the atmosphere at it's normal speed, yes.  It would not be going fast enough.  If sped up to the same speed as a satellite, it would act the same as a satellite.

Quote from: Yendor on December 19, 2015, 10:05:45 AM

1. A satellite is launched into orbit and it flies around the Earth.

at an average speed of 17,000mph.

Quote

2. An airplane flies off the runway and it too flies around the Earth.

at an average speed of 100-200mph.  Airliners cruise at 500-600mph.

Quote

3. Without getting on another subject, Let's say gravity tries to pull both satellites and airplanes back down to Earth.
4. Inertia keeps the satellite and an airplane from allowing gravity to pull them both back down to Earth.

Inertia keeps the satellite moving at that high-rate of speed while gravity pulls it toward Earth.  It continually misses, and there is almost nothing to slow it.

Inertia will let the airplane glide for a bit before dropping.  Without the constant thrust from the propeller, etc, wind resistance would slow it quickly.  Lift generated by the wings is what keeps it flying. 

Quote

It just seems to me that if an airplane could fly outside Earth's atmosphere, it would act no different then it does flying inside Earth's atmosphere.

At it's same atmospheric speed, it would drop quickly as there would be no air for the wings to provide lift.

 

Quote

The only way, that I can see a satellite in free fall is if inertia gives out and then gravity can pull it back down to Earth.

It is in free-fall.  Inertia keeps it moving sideways fast enough that is keeps missing the planet.  Thrust brought it up to that speed (or is used occasionally to keep it at that speed)

Quote

This too will happen with an airplane.

In the atmosphere, yes.  It will lose it's speed, which is required in addition to air for the wings to provide lift.  Outside the atmosphere at it's normal speed, yes.  It would not be going fast enough.  If sped up to the same speed as a satellite, it would act the same as a satellite.

1. & 2. That fast speed is not necessary. They say it has to be that fast so it can free fall around the Earth. Often times they show a cannon firing a cannonball to demonstrate it has to go that fast in order to miss the Earth and fly around it. You know that is not true because Airplanes fly just fine around the Earth going no wheres that speed.

3. & 4. What you say is the same as what I said except you say, "It continually misses". Well it does miss hitting the Earth, but that does not mean it is in free fall. An airplane misses the Earth and it is not in free fall.

5. The only reason an airplane can't fly outside the atmosphere is because the engines need air. If the airplane had a rocket engine like a satellite, (remember reading this from the website I gave you?), "A satellite's forward motion is controlled by rockets. When the rockets are not fired, inertia keeps the satellite going in one direction." The airplane would need no wings in space because there is no air in space. It would simply fly in a straight path because the rocket engine would provide the necessary inertia and gravity would keep it from flying away from the Earth.

6. Why do you insist on calling it free fall? If gravity is trying to pull an object down but inertia is overcoming the pull of gravity, then an object is simply flying. You see this everywhere. When a person jumps his muscles will get him off the ground, but gravity gets him back down. A person with stronger muscles can jump higher and further, but gravity will still pull him down. This is what is happening in space as well, only because of the vacuum of space, inertia is is much stronger because there is little resistance to slow the satellite down and gravity will not pull it down. When inertia does become weaker and gravity begins to pull it down, the rockets will kick in and boost the inertia and everything is back to normal again. There is no free fall here, only when they purposely want to bring it down. Free fall is:  Any object that is being acted upon only by the force of gravity is said to be in a state of free fall.  Wouldn't you think that if a satellite was in actual free fall, gravity would keep pulling and pulling it in towards the center of the Earth until it reached the Earth's atmosphere where it would eventually burn up? What would stop it from happening? The puny rocket engines they have on satellites sure would not stop it.
 
7. You are back to speed again. The speed of the satellite  is the speed they figured out they need to use in order to keep people believing satellites are free falling around the Earth.

If you don't believe what i believe that's fine. At this point in time it just seems to make sense to me and maybe no one else.

I'm confused. At first you were asking simple questions and now you are acting like you know everything. Which is it?

I'm confused. At first you were asking simple questions and now you are acting like you know everything. Which is it?

You get confused easy. Please try and keep up.