Artificial gravity in spinning space ship conumdrum

[KenJackson]

In discussions, and novels, about deep space missions, we frequently read of the plan to spin the spaceship to produce artificial gravity. This intuitively makes good sense.

But would it work in a ship that is very, very, very far away from any stars or other matter? That is, if the ship is spinning, relative to what is it spinning?

If the proximity to matter is irrelevant, then does the universe have some inherent sense of direction or "upness"?

 

[Shooting Star]

As far as we know, it would work. Also, there is only so far you can be from stars and other matter. The emptiest regions we see is probably between the galactic super clusters or possibly the "voids" between the complexes made by these, the “walls”. But these "empty" spaces, too, contain dark matter. So, if you are trying to invoke Mach’s Principle, it’ll be difficult to conduct any experiment “sufficiently” removed from matter in this universe.

The relevant spinning appears to be with respect to the "distant" matter. Exactly how the distant matter influences the inertia of an object is not known. But according to the qualitative results of Mach’s Principle, nearby masses also should influence inertia locally. This type of phenomenon was investigated by Lens and Thirring in the context of GR, and is known as the rotational frame dragging effect. The effect of local masses on the mass of a test body is also predicted in GR, but the effect is too small to measure with available methods.

Broadly speaking, the universe seems not to distinguish between uniform velocities but between accelerations with respect to the average distribution of matter.

 

[KenJackson]

Mach’s Principle

Ah! That is what I was looking for. Thank you.

 

[LURCH]

In discussions, and novels, about deep space missions, we frequently read of the plan to spin the spaceship to produce artificial gravity. This intuitively makes good sense.

But would it work in a ship that is very, very, very far away from any stars or other matter? That is, if the ship is spinning, relative to what is it spinning?

If the proximity to matter is irrelevant, then does the universe have some inherent sense of direction or "upness"?

I would say, no, the universe does not have an inherent sense of direction, nor of "upness," but it does have an inherent sense of inertial and non-inertial reference frames. The same "artificial gravity" effect could be achieved by providing a ship with a form of continuous thrust, resulting in continuous acceleration. It would not matter if the ship were near any massive bodies. The ship does not have to be accelerating "relative to" some other object. It need only be accelerating compared to an inertial frame of reference.

 

[nuby]

Is there even any scientific proof of this concept? If a space station is spinning rapidly around an axis in space .. simulated gravity would come from centrifugal force? I've heard lots of talk about this, but where is the proof? Does NASA have a video clip or experiment data?

 

[PatPwnt]

Yea there is proof; acceleration is a change in velocity. When you are spining around an axis, you are changing velocity from the centripetal force keeping you from traveling in a straight line. This force can feel just like like gravity, if you are far enough away from the center to where your height towards the center doesn't have a noticable effect on the force distribution on your body. Otherwise, I think your head would feel lighter while standing. But another thing would happen, if you threw a ball with equal velocity of the angular velocity of the ship(times the radius), but in opposite direction, it would just float above the surface as you spun around and it stood still relative to the center of mass of your ship. So, there would be strange things that made it not feel like gravity. If you wanted to toss something to your friend on the other side of the ship, you would have to throw it with a tangeant component to the ship's radius and opposite direction of your real velocity at that point, then it will reach him. So the effects would not be exactly like gravity. If you tried throwing it directly at him, you may just end up spinning around the axis and it landing in your face. Just like if you threw it straight up in gravity. If you were sitting down and stood straight up, you would probably fall over because your body's angular momentum stays the same while your center of mass moves in toward the center.

Have you ever been on one of these?
http://video.google.com/videoplay?docid=-1001294017951031404&q=centrifugal+machine&total=66&start=0&num=10&so=0&type=search&plindex=0"

Notice at the end of the video when he tries to walk towards the camera, he jerks over to his left.

 

[nuby]

PatPwnt, Thanks for that video, it was entertaining. But, it proves nothing really.

Please explain why:

1. This simulates the same effects that would occur in outer space.

2. Centrifugal force can't be the 'redirection' of gravity.

 

[Anticitizen]

It's not redirection of gravity, it's redirection of motion which happens to behave a bit like gravity to the person being spun.

 

[nuby]

Ok. Prove it. A video clip like the previous one (small scale) in space would be great.

 

[Anticitizen]

Why do you believe it would happen any differently in space than on land? The centrifuge on land is spinning fast enough (horizontally to the ground) to OVERRIDE the effects of gravity (in the vertical axis to the ground), it'd be the same in space, only easier, because there'd be nothing pulling the person downward.

To prove it to you, I'd have to launch a centrifuge into deep space, which is beyond my current budget I'm afraid.

 

[Anticitizen]

That is, if the ship is spinning, relative to what is it spinning?

To itself, or different parts of itself. If you picture the centrifuge from 'above', that is, your viewpoint in line with the axis of rotation but not rotating with the 'fuge, then you'll see that one side is moving 'left' and the other moving 'right' in regard to each other. I mean that in the same sense that one describes a watch hand moving to the 'right' once it passes the 9 o'clock mark, then curving back 'left' once it passes 3 o'clock.

 

[nuby]

Is it safe to say centrifugal existing in outer space is just an assumption?

 

[rbj]

But would it work in a ship that is very, very, very far away from any stars or other matter? That is, if the ship is spinning, relative to what is it spinning?

unlike translational velocity, which is completely relative (anyone flying around in a vacuum relative to someone else at a constant velocity has an equal claim to being "at rest" as anyone else at a constant, but different, velocity), rotational velocity is absolute. it's not spinning if the folks in the outer rim of the cylinderical spaceship are experiencing 0g. even if there were no heavenly vistas in which to base one's measurement of spin rate, with an accelerometer at a known location, one can determine the spin rate.

 

[Shooting Star]

Is it safe to say centrifugal existing in outer space is just an assumption?

Not in front of any qualified physicist, especially if he's bigger than you. Here, you have the whole internet shielding you.

What more can we tell you about the existence of centrifugal force? The earth, the Sun, Jupiter, to name a few -- all these bodies which are in "space" -- bulge out at the equator due to centrifugal force. The bulges are visible. These are your large scale experiments in space.

Please don't hijack this thread. If you have so much doubt, start a new one.
-------------------------------------------------------------
Dear Mentor/Admin,

Doesn't nuby's previous post violate the PF rules/guidelines? Someone may as well question Newton's laws of motion directly, instead of indirectly as member nuby is doing.

 

[nuby]

What more can we tell you about the existence of centrifugal force? The earth, the Sun, Jupiter, to name a few -- all these bodies which are in "space" -- bulge out at the equator due to centrifugal force. The bulges are visible. These are your large scale experiments in space.

That's not relevant, it's not 'outer space' .. centrifugal force on planets coexist with other forces, gravity, etc.

 

[KenJackson]

unlike translational velocity, which is completely relative (anyone flying around in a vacuum relative to someone else at a constant velocity has an equal claim to being "at rest" as anyone else at a constant, but different, velocity), rotational velocity is absolute. it's not spinning if the folks in the outer rim of the cylinderical spaceship are experiencing 0g. even if there were no heavenly vistas in which to base one's measurement of spin rate, with an accelerometer at a known location, one can determine the spin rate.

You hit the crux of my original question, but you seem to have answered it based on Newton's classical absolute space argument.

rotational velocity is absolute. it's not spinning if the folks in the outer rim of the cylinderical spaceship are experiencing 0g. This sounds like Newton's bucket argument.

I was pleased that someone mentioned Mach's Principle, which caused me to find the wikipedia discussion on the same. I am content to learn that Einstein grappled with the issue and decided that inertia originates in a kind of interaction between bodies. That is, (as I understand it) the presence of other matter (I guess all matter in the universe) determines what is and is not spinning.

 

[TVP45]

Is it safe to say centrifugal existing in outer space is just an assumption?

No, it is not an assumption. The European Space Agency built a centrifuge for space (obviously not deep space) and a copy was flown by NASA.

Start by Googling NASA JSC. Specifically, you might also look at work done by Scott Wood.

 

[Shooting Star]

Archaic argument

... rotational velocity is absolute. it's not spinning if the folks in the outer rim of the cylinderical spaceship are experiencing 0g. even if there were no heavenly vistas in which to base one's measurement of spin rate, with an accelerometer at a known location, one can determine the spin rate.

Absolute with respect to what? The mean of the distant matter? Or Absolute Space?

If there's a germ of truth in Mach's Principle, which the scientific community does believe there is, then a massive rotating shell spinning around you should produce a centrifugal force similar to what is produced by you spinning wrt the background of the distant matter.

Even otherwise, spinning near a massive body gives rise to different effects than spinning in a relatively mass free region, and the accelerometer would show different readings.

 

[nuby]

http://www.artificial-gravity.com/ (lots of references)

http://spaceflight.nasa.gov/gallery/video/skylab/skylab2/mpg/skylab2_mission1.mpg (video)

 

[nuby]

Does that video prove "artificial gravity" is possible?

 

[Andy Resnick]

I'm a little confused- are people wondering if the concept is sound, or if it's practical to actually construct such a device?

Is the concept sound (the science)- yes.
Is the device practical (the engineering)- no.

 

[yuiop]

Is it safe to say centrifugal existing in outer space is just an assumption?

Here is a sort of proof that it is not just an assumption:

Imagine two large disk shaped spaceships traveling alongside each other. Each is spinning around their own axis of symmetry parallel to the direction of motion, but rotating in opposite directions with respect to each other. As they move far away from any massive body, which will stop rotating (as you suggest)? If neither stops rotating how would they account for the lack of "apparent centrifugal force" in both spaceships (as you are suggesting) when it is obvious to any local observer (spinning or not) that at least one of the spaceships IS rotating? If both spaceships stop rotating with respect to each other where has the stored rotational energy gone?

 

[LURCH]

Does that video prove "artificial gravity" is possible?

Yes, the video proves that generating artificial gravity in space via "centrifugal force" is not only possible, but has been done. That is what kept the astronaut's feet on the "floor." It was obviously not a full G, but it was keeping him "down" on the track.

 

[nuby]

When I hear "artificial gravity" I think of something out of 2001: A Space Odyssey.. The rotating space craft, with people walking around inside of it. This is not possible. Real "artificial gravity" is created in a smaller centrifuge, with an astronaut strapped inside of it.. Without the straps (or physical motion of astronauts) there will not be a centrifugal force on the astronauts.

This leads to a few more questions:
Why are the astronauts not experiencing the same affects as they would on say a "gravitron" (carnival ride) or in their training centrifuge? Are they experiencing "real" centrifugal force without centripetal force? Can centripetal force exist without gravity?

 

[TVP45]

You'll need to do some research on some of your questions. The only reason anyone cares about artificial gravity is the effect weightlessness has on astronauts. So, the place to look for your answers is at the Johnson Space Center, beginning in the Human Adaptation labs.
http://hacd.jsc.nasa.gov/
You might also look at Krug Life Sciences to see some other work being done there.

 

[yuiop]

When I hear "artificial gravity" I think of something out of 2001: A Space Odyssey.. The rotating space craft, with people walking around inside of it. This is not possible. Real "artificial gravity" is created in a smaller centrifuge, with an astronaut strapped inside of it..

Why do you think centrifugal force is felt in a small centrifuge but not in a large centrifuge?

Without the straps (or physical motion of astronauts) there will not be a centrifugal force on the astronauts.

The astronaut is running in the video because the space station is not spinning. Running inside the rim of a non spinning station has the same effect as standing in a spinning station.

This leads to a few more questions:
Why are the astronauts not experiencing the same affects as they would on say a "gravitron" (carnival ride) or in their training centrifuge? Are they experiencing "real" centrifugal force without centripetal force? Can centripetal force exist without gravity?

They would experience the same effects as in a gravitron if the station was spinning, (but it was not). I suspect you have not read or thought about any of the responses posted above.

 

[nuby]

They would experience the same effects as in a gravitron if the station was spinning, (but it was not)

You are wrong. Unless the astronauts are physically attached to a spinning "centrifuge", or propelling themselves forward (i.e. previous video) they will not experience any sort of "artficial gravity" at all.

 

[Atomsk]

You are wrong. Unless the astronauts are physically attached to a spinning "centrifuge", or propelling themselves forward (i.e. previous video) they will not experience any sort of "artficial gravity" at all.

You're right but as soon as they touch down to the rotating "ring" if you will the tangential velocity will propel them in the direction of the ring and then the ring itself will keep changing their velocity (acceleration) to keep the person in an artificial gravity. Artificial meaning it's not real, it just seems like gravity because objects are held to the surface without restraints.

I don't understand what you're getting at. It's the centripetal force that let's the person walk on the inner surface of the ring. Maybe they have to acclimate themselves to it after first touching down but aside from that is your argument that it's not the definition of gravity or that it's not possible. I'm not getting a streamlined thought from your posts.

 

[Shooting Star]

When I hear "artificial gravity" I think of something out of 2001: A Space Odyssey.. The rotating space craft, with people walking around inside of it. This is not possible. Real "artificial gravity" is created in a smaller centrifuge, with an astronaut strapped inside of it.. Without the straps (or physical motion of astronauts) there will not be a centrifugal force on the astronauts.

Arthur C. Clarke was one of the greatest thinkers of all times. He was the kind of scientist who could envision and extrapolate quite a few steps ahead of the boundaries of accepted science at any time. Nobel laureates walked softly when he was around. I am not even going into his writing skills and writing prowess, which went far, far beyond Science fiction by the way.

The scientific details of his so called SF books are phenomenally accurate. The scenario of both "2001: A Space Odyssey" and "Rendezvous with Rama" comes to mind for the sheer amount of technical analysis of rotating space stations. These were written in times when very few people even imagined such things.

You, a Physics ignoramus or a lunatic without a leash, dare comment in one sentence on a great work by a great man which your brain does not have the logic circuits to process. If the things described in the book were not possible, then Arthur C. Clark would not have written about them. Do you understand?

Arthur C. Clark passed away just a month back, on 19th March, 2008. I feel that somebody near to me is no more.

You evidently are much younger than me, and that is why, though being irked, I have never commented on your writings personally. Your youth does not give you the leeway to affront the brilliant works of a great man. Threads have been locked for much less than have been tolerated from you. I advise you to take some time off and learn basic Physics.

If this mail seems to be rude in any respect, then it is meant to be.

 

[Danger]

Maybe it would be more appropriate to refer to the centrifugal effect as 'pseudo-gravity' rather than 'artificial gravity'. The latter implies to me some sort of graviton or gravity wave generation which would induce true gravity, while the former just provides a reasonable approximation thereof.

 

[yuiop]

You are wrong. Unless the astronauts are physically attached to a spinning "centrifuge", or propelling themselves forward (i.e. previous video) they will not experience any sort of "artficial gravity" at all.

As Danger pointed out the "artificial gravity" is just an aproximation of the real thing. If an astronaut managed to avoid the spinning rim for the whole trip then he could avoid being pulled down. (He is actually in a form of internal orbit). But if there is air inside the space station (as there usually is) then the air will gradually be dragged around into synchronisation with the rim and eventually the astronaut too would be dragged by the air and start to "fall".

If he was standing on the spinning rim and let go of a ball, guess where the ball will go?

A) Hover near his hand.
B) Move in an internal orbit like the astonaut before he touched down.
C) Drop towards his feet and stay on the rim after a couple of bounces.


Hint: It's not A or B ;)

 

[nuby]

As long as the astronaut was connected to the rim, the ball would have a curved trajectory toward the ground/rim ..

If the answer is "C" and the ball would drop straight towards his feet. What force would keep the ball adjacent to the floor below?

 

[Shooting Star]

There was some fruitful discussion on these things some time ago in https://www.physicsforums.com/showthread.php?t=204597" thread. The discussion was all right up to post #33.

 

[TVP45]

I think perhaps Nuby is looking for an argument rather than an answer.

 

[nuby]

I just think "artificial gravity" (walking around in space) is just a myth, and pure science fiction/speculation. And I'm interested in finding out why it should or should not work. If I wanted to argue I would have responded to Shooting Star's previous post.

 

[Atomsk]

When talking about the person dropping a ball dropped inside the "artificial gravity" in reference to the person inside the ring the ball would look like it fell straight down. The ball in question will already have the tangential velocity of the spinning ring that both person and ball are in motion with.

I already asked what your point was, that using rotational acceleration to simulate gravity for one that is in sync with the object that is rotationally accelerating is not artificial gravity, or was your point that rotational acceleration will not even simulate gravity. I think we all agree that it's not real gravity like what we see as a result of mass being present but it's the best approximation we can currently realize.

The problem being, you are stating that it's not artificial gravity but you aren't stating any evidence to back up your claim and then continue to avoid clarifying your statement.

 

[Shooting Star]

I just think "artificial gravity" (walking around in space) is just a myth, and pure science fiction/speculation.

Oh, good lord, NUBY, what exactly do you mean by space walking? We hear that astronauts sometimes go for space walks, and that means nothing more than that they are tethered to the ship and have gone out do some work on the ship (EVA). They are essentially just "floating" around in space, though actually they are in free fall around Earth if that vehicle happens to be orbiting earth.

Do you mean that by "artificial gravity"? Also, let me say once more that there is nothing called artificial gravity.

Science fiction and speculation do not share the same status, as you seem to imply in the above post.

If you do want to discuss space walks using artificial gravity, at least open a new thread as I had requested you before.

 

[nuby]

Atomsk,

I'm thinking that centrifugal force might behave differently in space than it does on earth, and that 'artificial gravity' (ie 2001: A Space Odyssey) would never work due to the coriolis effect. I'm not arguing the terminology, just the theory.

 

[Doc Al]

I'm thinking that centrifugal force might behave differently in space than it does on earth...

Be advised that personal speculation is not permitted here.

 

[TVP45]

Artificial gravity (that is the correct term and needs not to be set off in quotes) is very real, is practical, and is being widely studied (JSC, Cleveland Clinic, Univ. of Texas, Mt. Sinai, etc.). It is not about tossing balls in the air; it is about the physiological effects on humans of living for long periods in microgravity.

In a very large radius ship, as in 2001, one could create an artificial gravity that closely mimics real gravity and a ball would fall almost correctly. A ship that large is out of the question now; it may be built, perhaps within your lifetime, and you'll be able to see demonstrations of that gravity. In the meantime, we all have to be satisfied with short-arm centrifuges.

I earlier posted several links to the work being done at JSC. A centrifuge has been flown, and I mentioned that. There are a ton of links to papers by respected scientists on the sites I gave you. Have you looked at those?

YouTube is fun but not a citation.

 

[nuby]

It wouldn't be hard for NASA to demonstrate artificial gravity on a small scale, and there are tons of videos out there with other experiments. Where is the one for artificial gravity?

(27 seconds in) shows a coriolis affect

 

[TVP45]

It wouldn't be hard for NASA to demonstrate artificial gravity on a small scale, and there are tons of videos out there with other experiments. Where is the one for artificial gravity?

(27 seconds in) shows a coriolis affect

Are you following any of the links I've suggested? NASA has created artificial gravity hundreds (thousands?) of times. Of course there is a coriolis effect; again, if you look at the sites I've suggested, you'll find a number of papers referencing the problems that creates.

 

[Shooting Star]

Artificial gravity (that is the correct term and needs not to be set off in quotes) is very real, is practical, and is being widely studied (JSC, Cleveland Clinic, Univ. of Texas, Mt. Sinai, etc.).

(I think you and I have gone through this before.)

I wanted to avoid that term since there is a lot of confusion going around here. How can somebody confuse "space walks" with "walking in artificial gravity"? Also, "artificial gravity" may suggest something like Star Trek gravity (which would be truly artificial gravity), so I thought I would clarify matters.

The artificial gravity we are talking about here is the effect of inertial forces in any non-inertial frame. I sincerely hope it is clear now.

Let me sum up with what we are dealing here:

Whenever there is an accelerating frame, there are inertial forces, whose effects on a small region and over a short time can be approximated by a uniform gravitational field. (This sounds like the equivalence principle, which it is actually, but all discussions here are within the Newtonian scenario.)

These may be identified as the centrifugal force or the Coriolis force in a uniformly rotating frame. In a uniformly accelerating frame in a straight line, it will be an effective gravitational field in the opposite direction, as in elevators/lifts. If the acceleration of the frame is arbitrary, the inertial forces will be different from these familiar examples. It may be very difficult to calculate and also to predict what effects will be felt by a human being under such arbitrary forces. Also, remember that for a human being to feel anything, he should not be in free fall in that frame, which would just be equivalent to moving with constant velocity wrt some IFR, but has to be stationary wrt the non-IFR. Then only he can feel the effect of inertial forces.

In a very large radius ship, as in 2001, one could create an artificial gravity that closely mimics real gravity and a ball would fall almost correctly.

That is not correct. If you push something from the centre toward the rim, the trajectory will not seem like a straight line in the frame of the ship. We have already discussed this https://www.physicsforums.com/showpost.php?p=1546281&postcount=29".

Similarly, in a small centrifuge, the variations are much more over a short distance, than say, over the Earth for the same distance (due to Earth's rotation).

I earlier posted several links to the work being done at JSC. A centrifuge has been flown, and I mentioned that. There are a ton of links to papers by respected scientists on the sites I gave you. Have you looked at those?

I fail to understand why we have to give an example of something that NASA has built to prove the existence of inertial forces. I know that you are interested in microgravity, but that has nothing to do with the discussion here. (Remember, you can take the horse to the water but you cannot make it drink.)

I don't think you and I have any argument, just some confusion over terminologies. Arguing here about centrifugal forces is just adding fuel to the fire. If you really feel you have to disagree, PM me, as I want to unsubscribe from this thread.

 

[TVP45]

I think unsubscribing is a wonderful idea. I'll join you.

 

[Shooting Star]

Atomsk,

I'm thinking that centrifugal force might behave differently in space than it does on earth, and that 'artificial gravity' (ie 2001: A Space Odyssey) would never work due to the coriolis effect. QUOTE]

Hold on for a moment. (I was about to unsubscribe when I read this again.) Do I see a glimmer of hope yet?

Nuby, why don't you just explain exactly what you meant when you wrote the above sentence? Did you mean that if I let a ball drop in a big rotating space ship, it will not fall straight toward the rim? Feel free to explain in detail, but just stick to this point.

 

[HallsofIvy]

As long as the astronaut was connected to the rim, the ball would have a curved trajectory toward the ground/rim ..

If the answer is "C" and the ball would drop straight towards his feet. What force would keep the ball adjacent to the floor below?

The ball would not drop straight toward his feet. "Coriolis" force would make its trajectory curve a little bit. The ball's initial rotational speed would be less than that at the astronaut's feet. That's one difference between "gravity" simulated by spinning and true gravity. That's only noticable in a very large volume.

It is, of course, the "centrifugal force" that would keep it on the floor. Yes, I know that centrifugal force is "ficticious". It is a convenient way of saying that the ball, with its instantaneous velocity parallel to the direction of rotation would attempt to continue in that straight line and is prevented from doing so by the "centripetal" force the floor exerts on it.

There would be no force toward the floor if the astronaut were not on the floor and were not rotating around the axis with the rest of the ship, then there would be no "fake gravity" force. But how would he get there? If he jumped up from the floor, he would still have the floors rotational velocity.

Oh, and to answer the question that was posed in the very first post, "If the ship were very far from any star, what would it be rotating with respect to?", with respect to its own axis, of course. Velocity is relative. Rotation involves an acceleration and is not relative.

 

[LURCH]

If it sheds any new light, remember that there is Coriolis effect on Earth as well. So, if you drop a ball while standing on the ground, it will not really fall in a perfectly straight line downward, will it? Its path will be slightly curved due to Coriolis, and the fact that your hand is slightly farther from the center of rotation than the ground toward which the ball falls. Even on Earth we are experiencing gravity in a rotating frame, and we have certain effects acting upon us as a result of that rotation. But for the most part, we can ignore these effects because they are vanishingly small.

Likewise, artificial gravity generated by rotation would have some Coriolis effects involved. And, these effects would be greater than we exerience on Earth (because the rotating frame is much smaller). But, for the most part, the effect could still be ignored (just like it is here on Earth). Artificial gravity is, after all, only an approximation of real gravity and, for every-day use, it works perfecty well. You could put your feet on what others would consider the "wall" of the ship, and walk around and feel perfectly normal calling it the "floor." You could put a meal on a plate and it would stay there, and someone outside the ship would say it is stuck to the wall by centrifugal force, but to you it would seem to be sitting on the plate in a perfectly normal way. You could drop a ball and it would fall to the floor at your feet. If you had precise enough instruments, you could measure some curve to that drop, but you could do that on Earth, too.

As for centrifugal force behaving differently in space than it does on Earth, it just doesn't. The scientists on the ISS have been conducting experiments using a centrifuge pretty much since the staion went operational. Centrifugal force works just the same up there as it does down here.

 

[Shooting Star]

It is, of course, the "centrifugal force" that would keep it on the floor. Yes, I know that centrifugal force is "ficticious". It is a convenient way of saying that the ball, with its instantaneous velocity parallel to the direction of rotation would attempt to continue in that straight line and is prevented from doing so by the "centripetal" force the floor exerts on it.

It would be extremely difficult to keep a ball on the outer "floor" of a rotating frame just by centrifugal force alone, as that would be a very unstable situation. It is generally the friction in conjunction with the centrifugal force which will keep the ball stationary wrt the floor, or else the ball would have to be clamped down. As on a horizontal surface of earth, things stay in their places because of friction and gravity, otherwise the rotation of the Earth would cause them to slip. Think of that the next time you are typing and your computer is not sliding off.

Oh, and to answer the question that was posed in the very first post, "If the ship were very far from any star, what would it be rotating with respect to?", with respect to its own axis, of course. Velocity is relative. Rotation involves an acceleration and is not relative.

Read posts #2 and #18.
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Hey NUBY,

Anticipating an answer from you is the only thing that's keeping me here.

 

[nuby]

Shooting Star, Like other have explained, I think the coriolis effect will be at play in a rotating spaceship (and on earth). But, I'm wondering if the magnitude of the effect is a greater in space, and how it is calculated in space or on land (moon, earth, etc).

 

[Shooting Star]

Shooting Star, Like other have explained, I think the coriolis effect will be at play in a rotating spaceship (and on earth). But, I'm wondering if the magnitude of the effect is a greater in space, and how it is calculated in space or on land (moon, earth, etc).

(Nuby, if I have ever seen hijacking, this takes the cake.)

I have this morbid curiosity to know why you think that the Coriolis effect is different in what you call "space"?

You did not answer the question I had asked you in my last post. I am asking you two more.

1. What is "space", according to you?

2. Can we explain all phenomenon happening in the rotating ships without invoking centrifugal or Coriolis force, from the point of view of an IFR?

You can read https://www.physicsforums.com/showpost.php?p=1546281&postcount=29" discussion, which I had mentioned earlier. (It is a simple and very short description of the two points of view.)

Do answer the question in my last post by just saying yes or no.