[Jaaanosik]

Three CD players would behave as one CD player if the axes are aligned and they spin in the same direction.

No they would not, because the angular momentum would be three times higher.

But it seems you have more or less answered the right question

The CDs would spin inside and the CD players would spin in the opposite direction in ideal conditions.
The total net momentum would be 0.

OK, so the total angular momentum would be zero.

So, if you tapped on it like in the video, what would happen?
(Imagine that the finger tapping it is moving at the same speed tangentially as the player so it doesn't impart a torque.)

Do you agree that , because the overall  angular momentum is zero, it will tumble and there will be no "gyroscope" effect?

I am not sure what you mean by tumble, no "gyroscope" effect, please, be more specific.

[Bored chemist]

Do we have an agreement that the system demonstrates different attributes, the system behaves differently due to the internal motion of inner parts even thought the total net angular momentum is the same before the external impulse?

That's essentially what I'm asking about.

"Tumbling" is rotating in a disorganised way.
 

[Bored chemist]

Imagine I have two pairs of players taped together feet to feet so that (as long as the disk speeds are the same) the angular moment sum to zero.

I set both disks in one pair spinning.
I leave the other pair switched off.
And, since I'm in zero gravity Ican just put the two pairs in front of me and watch them.
They do nothing, because no (significant) external force is action on them.

Imagine I tap both of the pairs on the corresponding corners.

Do you think they will behave differently (because one of the pairs contains spinning things, and the other pair does not)?

[Jaaanosik]

Imagine I have two pairs of players taped together feet to feet so that (as long as the disk speeds are the same) the angular moment sum to zero.

I set both disks in one pair spinning.
I leave the other pair switched off.
And, since I'm in zero gravity Ican just put the two pairs in front of me and watch them.
They do nothing, because no (significant) external force is action on them.

Imagine I tap both of the pairs on the corresponding corners.

Do you think they will behave differently (because one of the pairs contains spinning things, and the other pair does not)?

They will behave differently.
Considering we are applying an external momentum, the distribution to all parts of these two systems is not going to be the same therefore they will behave differently.
If one is 'rigid' body and the other has moving parts, they have to behave differently.
I am not saying the external momentum will 'get lost', I am saying it will distribute through the system differently and therefore the systems will move (translate/rotate) differently.

[Bored chemist]

If one is 'rigid' body and the other has moving parts, they have to behave differently.

They are not "rigid". The CDs are still in the players and can rotate. Switching them off doesn't stop the bearings working.

[Bored chemist]

They will behave differently.

I am really rather sure that they will not behave differently.

[hamdani yusuf]

(Am I The only one who worries about anyone in zero G who thinks that taping 3 CD players together  at right angles is ter than taping them together with the axes aligned?)

If their axes are all aligned, then the system won't resist spinning of the player caused by external force which is perpendicular to (but doesn't intersect with) that axis.

[hamdani yusuf]

Multiple axis rotation has been explored extensively in game programming. Here is a good example.
https://gamedev.stackexchange.com/questions/136174/im-rotating-an-object-on-two-axes-so-why-does-it-keep-twisting-around-the-thir


So when the disc rotates in one direction, the disc player rotates in opposite direction to compensate for the angular momentum. Combining the second disc player orthogonally to the first can create rotation on third axis. If the directions are correct, it is possible to cancel out combined rotation on two axes by applying rotation on third axis.

[puppypower]

One observation that nobody has mentioned, is that the earth's core spins faster than the surface of the earth. This was discovered in 1996 but has been ignored by the status quo, since too much credit would have required a complete revision of current earth theory.

Bollocks
The theory actually predicted that the core spins faster in 1995.
This was then measured in 1996.

If we accept this data as true, then we need to revise the earth sciences since no models anticipated this,

Just not true.

" A 1995 model of Earth's dynamo predicted super-rotations of up to 3 degrees per year; the following year, this prediction was supported by observed discrepancies in the time that p-waves take to travel through the inner and outer core."
From wiki
https://en.wikipedia.org/wiki/Inner_core_super-rotation

The rest of your post makes no more sense than would be expected, given that it's based on errors.

The question I asked and tried to answer was, how does the observation that the core of the earth is spinning faster than the surface, impact the rest of earth science, all the way to global warming? And why hasn't the status quo altered the rest of the theory to accommodate the implication of a moon sized object within the earth spinning faster than the surface? At the very least we now have a huge object creating viscoelastic friction, which creates heat, eddies, convection and a moving phase boundary. Why is current earth theory not banished to alternate theory until it ups its game with the new data? Dies science has a grandfather clause?

The explanation for the core's higher rotation is supposedly based on the cooling of the fluid outer core. This causes this fluid iron material to contract into the solid inner core. Like the skating pulling in their arms, the angular momentum is conserved, so the result is faster spin.

The problem with this model is why isn't the surface and mantle contracting to fill in the space left behind by the contracting outer core? This global wide contraction should amply the friction. Has anyone thought this through, and are surface observations consistent with these extras? When a liquid changes phase into a solid, there is heat of fusion given off. Where is this extra heat going?

I developed an integrated model that goes from sun to core via the continuity of water, since the current theory does make all the needed connections. Should existing theory be sent to alternate theory, since it lacks the core observations and implications as part of its model?

Another observation, that was noted, at about the same time, was the earth is denser north to south compared to east to west. The earth bulges at the equator, but that average density is lower east to west. The earth is shorter north to south, but denser north to south. This was proven measuring the speed of seismic waves in various directions. Why is the extra material at the equator not packing the earth denser east to west via gravity? Does it have to do with maximum electron flow and the induced phase characteristics at the equator?

Mars does not rotate very fast and it is called the red planet due to the iron. What happened to its iron core rotation? Has the surface water been commandeered to the iron core?

[Bored chemist]

The question I asked and tried to answer was, how does the observation that the core of the earth is spinning faster than the surface, impact the rest of earth science, all the way to global warming?

The questions you actually asked were.

Can heat impact the rotation of the earth? If the core is driving the rotation, then the question becomes does heat increase reaction rate and thereby speed core rotation and the secondary affect this will cause?

The answers are
Not directly
 and
"If the core is driving the rotation..."
It isn't.

[Bored chemist]

And why hasn't the status quo altered the rest of the theory to accommodate the implication of a moon sized object within the earth spinning faster than the surface?

Because it doesn't actually make a difference to us here on the surface.
You would need to explain exactly what "theory" you think needs updating.
Obviously the theory that they used to predict the rotation of the core  does not need to be updated due to the rotation of the core.

What do you think they have got wrong?

[Halc]

The question I asked and tried to answer was, how does the observation that the core of the earth is spinning faster than the surface, impact the rest of earth science, all the way to global warming?

There's no implication to global warming. The core has been rotating faster since forever, and global warming is a new thing in the last century. The core dynamics has not changed in the last century.

And why hasn't the status quo altered the rest of the theory to accommodate the implication of a moon sized object within the earth spinning faster than the surface?

What theory needs alteration?  What implications have you envisioned that were not always there?

At the very least we now have a huge object creating viscoelastic friction, which creates heat, eddies, convection and a moving phase boundary.

The model has always known about the heat generated within. Where do you think geothermal energy comes from?  This thermal energy drives all the processes including the core rotation, so that rotation can't create new heat. It rotates because of the heat.

The explanation for the core's higher rotation is supposedly based on the cooling of the fluid outer core. This causes this fluid iron material to contract into the solid inner core. Like the skating pulling in their arms, the angular momentum is conserved, so the result is faster spin.

Exactly.  You put a pot of water on simmer, and the water moves around as it heats at the burner (the core), and cools at the surface. The result is convection motion. Add spin to it and you'll get the rotation predicted due to Coriolis force.
A hurricane works the same way: Heat input causes convection (upward) of warm air, with colder air moving downward. The effect makes a hurricane spin very fast in the middle without any torque being applied in that direction. The friction from the spin doesn't make the heat. The heat drives the spin.

The problem with this model is why isn't the surface and mantle contracting to fill in the space left behind by the contracting outer core?

Why would the outer core be contracting when there's a stove cooking it from below? That doesn't sound like an equilibrium state to me. This contraction is something you're making up. The Earth isn't losing mass so it maintains its size. There's no empty space being 'left behind'.

Has anyone thought this through, and are surface observations consistent with these extras?

Try thinking it through yourself first.

When a liquid changes phase into a solid, there is heat of fusion given off. Where is this extra heat going?

Probably into the melting of other solids back into liquid. It's in equilibrium, remember?

Mars does not rotate very fast

Pretty much same rotation rate as Earth, so we must not rotate very fast either. Not sure where the threshold of 'very fast' is. It you want one that rotates slowly, try Venus.

Has the surface water been commandeered to the iron core?

Why would low density water find its way below higher density materials?

[Jaaanosik]

They will behave differently.

I am really rather sure that they will not behave differently.

No, they will behave differently!

[Halc]

They will behave differently.

I am really rather sure that they will not behave differently.

No, they will behave differently!

Jano, you really need to be more precise, since there is no context left to criticise.
So what systems are you talking about (one running, one not presumably). What state are they in, and what force is being applied?  Just force?  Torque?  In what way does the running system behave differently than the non-running one?

I mean, I agree with you. The running one probably has a little yellow light on and has a display that counts the time where it is in the music, and the not-running one doesn't have these.  I don't think you're talking about those kind of differences, but with a childish response like that, it's all I have to go on.
So if you assert that it behaves differently, say how exactly, and if it can be shown to violate a known conservation law, you're probably very very wrong.

[hamdani yusuf]

Imagine I have two pairs of players taped together feet to feet so that (as long as the disk speeds are the same) the angular moment sum to zero.

I set both disks in one pair spinning.
I leave the other pair switched off.
And, since I'm in zero gravity Ican just put the two pairs in front of me and watch them.
They do nothing, because no (significant) external force is action on them.

Imagine I tap both of the pairs on the corresponding corners.

Do you think they will behave differently (because one of the pairs contains spinning things, and the other pair does not)?

They will behave differently.
Considering we are applying an external momentum, the distribution to all parts of these two systems is not going to be the same therefore they will behave differently.
If one is 'rigid' body and the other has moving parts, they have to behave differently.
I am not saying the external momentum will 'get lost', I am saying it will distribute through the system differently and therefore the systems will move (translate/rotate) differently.

Considering that the attachements are feet to feet, the discs inside the pair will rotate in the opposite direction, hence cancelling their angular momenta. So although the pair has two rotating discs inside, the angular momentum of the system is 0. Which is the same as the pair with non-rotating discs. Practically, it is still possible to notice the difference, which can be caused by flexibility of the mechanical connections such as the bearings, motor supports, wrapping tapes, etc.

The other case shown in the video where there is only one player with a rotating disc inside, the angular momentum of the disc is not canceled. Hence it will resist torque which would change the direction of its rotation axis. Similar case would happen if the pairs are attached feet to top.

[Bored chemist]

They will behave differently.

I am really rather sure that they will not behave differently.

No, they will behave differently!

OK,
I just checked; a CD has a mass of about 16 grams or 0.016Kg
0.06 M diameter
spins at 5 revs per second.
I = 1/2 M r^2

1.152 x10^-4 Kg m2

The angular velocity is 2* pi * 5  radians per second
31.4 rad/s
So the angular momentum of the rotating CD is
3.61 *10^-3 kg m^2 /s

Now that CD is made up of lots of protons, neutrons and electrons.
 Each of those has its own angular momentum (You might realise  now , why I was asking about a tonne of randomly oriented CD players in a box).

The mementa of those  particles are tiny.
 For the each particle , I is ½ ħ

1.58 x 10^-24
But there are lots of them
Thankfully, it hardly matters what elements the CD is made from.
The neutrons and protons have very similar weights-  about 1.7 X10^-27 Kg and they make up most of the mass (0.016 Kg)
So the disk has about 9.4 * 10^24 protons and neutrons
And it's got roughly half that many electrons.
So that's about 1.5 * 10^25 particles
So, if you are right about the momenta of components having an effect on the whole body, the subatomic particles in a CD have a total angular momentum of
1.5 * 10^25 * 1.58 x 10^-24
About 22 kg m^2 /s

And that's about 6000 times higher than the angular momentum of the CD due to its rotation as a rigid body.

So, if you were right, a CD would be a very effective gyroscope, even lying on teh table before you started spinning it (and, indeed, for any practical speed,  rotating it wouldn't make much difference).

On the other hand, my contention is that the angular momentum of a composite body is the vector sum of the momenta  of the components of a the body. Unless those are carefully aligned, they usually sum to zero.
And so, for the pair of CD players, just like for the non rotating CD, there's no "gyroscope" effect.

You should have answered my question about a box full of CD players.

[Jaaanosik]

They will behave differently.

I am really rather sure that they will not behave differently.

No, they will behave differently!

Jano, you really need to be more precise, since there is no context left to criticise.
So what systems are you talking about (one running, one not presumably). What state are they in, and what force is being applied?  Just force?  Torque?  In what way does the running system behave differently than the non-running one?

I mean, I agree with you. The running one probably has a little yellow light on and has a display that counts the time where it is in the music, and the not-running one doesn't have these.  I don't think you're talking about those kind of differences, but with a childish response like that, it's all I have to go on.
So if you assert that it behaves differently, say how exactly, and if it can be shown to violate a known conservation law, you're probably very very wrong.

Halc,
yes, I do not have time to write long responses every day.
I found some time, here it is.

Let us consider two CD players with feet sides attached, taped, CDs not spinning.
CDs are either locked as a rigid body or they have friction-less bearings.
We apply the external forces as per the image, in the CDs parallel plane.
The plane goes through the feet touching points.



The CD players start to rotate, the CDs either rotate with the CD players if they are locked or they are not if the friction-less bearings are used.
This is the first example where the CD players with locked disks will rotate with smaller angular velocity compared to friction-less bearings setup where CDs will not start to rotate inside.
This is what I meant when I said: "The external momentum will distribute through the system differently and therefore the systems will move (translate/rotate) differently."

When the CD players are ON then we need to consider the 'elasticity' of EM field of the motors.
One CD will be accelerated and the other will be decelerated when we apply the same external momentum as per the image.
The electric motor EM fields are not going to respond in the same way.
What I mean is that if stepper motors were used then we might observe steps 'skipping' based on the load being applied in the opposite direction of the running.
The skipping is not going to be the same on both motors because the external momentum is accelerating one CD and decelerating the second one.
Again: "The external momentum will distribute through the system differently and therefore the systems will move (translate/rotate) differently."
Jano

[Jaaanosik]

So, if you were right, a CD would be a very effective gyroscope, even lying on teh table before you started spinning it (and, indeed, for any practical speed,  rotating it wouldn't make much difference).

On the other hand, my contention is that the angular momentum of a composite body is the vector sum of the momenta  of the components of a the body. Unless those are carefully aligned, they usually sum to zero.
And so, for the pair of CD players, just like for the non rotating CD, there's no "gyroscope" effect.

You should have answered my question about a box full of CD players.

My post above shows what you missed.
Just think how different "gyroscope" effect is going to be for the spinning analysis.
The CDs are not going to have the same gyro effect.

[Bored chemist]

When the CD players are ON then we need to consider the 'elasticity' of EM field of the motors.
One CD will be accelerated and the other will be decelerated when we apply the same external momentum as per the image.

Once the disks are spinning then the motors have no work to do (apart from overcoming bearing losses which, in principle could be practically zero).
So you can switch the motors off at that stage.
There's no EM field needed.
So there's no need to consider any elasticity it might have.

My post above shows what you missed.

No
It shows that you do not understand physics.

[Bored chemist]

We apply the external forces as per the image, in the CDs parallel plane.

This is what I meant when I said: "The external momentum will distribute through the system differently and therefore the systems will move (translate/rotate) differently."

Why did you talk about that?
The question was about what happens after the disks are spinning.

There's a difference between the case of having the disks locked in place or not.
But since we are talking about CD players, and since I talked about being able topers play on the remote control, and get the disks spinning, it is clear that we are talking about the case where the discs can rotate.

Why are you talking about some nonsensical system where the discs won't play?