[Jaaanosik]

(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?)

Anyay, you are missing the point, and I suspect it's deliberate.

Imagine that the CD player has an IR remote control and is running on batteries.

You set it in front of you in zero G then, using the remote control, you press "play".

What happens?

If all is well balanced (ideal) then the discs will spin inside and the structure of CD players stays as is.

Now, do you agree there is a difference in the system response to the impulse as I described it?

[Halc]

We have been here before.
We discussed it, never came to a conclusion a few months back.

Yes, but what is the relevance of this to this topic?  The other topic was a sort of denial of angular momentum conservation, so since you've been doing that here, I suppose it is related.

The 3 CD players at 0:49s when the CDs are not spinning inside.
There is an external impulse to the system of connected 3 CD players when they are not running.
The system center of mass moves/translates at velocity v1.

As it should given an external force that you describe.  The force is off center, so the 'brick' acquires nonzero angular momentum.  No surprises.

The CDs are spinning inside at 0:55s.

This is the part BC gets at in his reply.  They don't show the external torque being applied to the assembly. The thing has angular momentum at 0.57s, so it cannot have gone from the prior scene to the one at 0:57 without an external torque being applied. You're not denying this (yet), but I want to explicitly point this out.

There is an external impulse (it appears to be the same magnitude, but off center)  to the system of connected 3 CD players when the are running (CDs are spinning inside).
The system does not start to rotate. The system wobbles.

The impulse applies a small torque to the assembly and thus must alter its angular momentum, which yes, results in the wobble you see.

The system center of mass does not move/translates at velocity v1 (magnitude).

Every tap changes the linear velocity of the center of mass of the thing. Are you denying that here?

The system center of mass is resisting the straight line motion/translation.

Nonsense. That is a denial of Newton's second law.

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?

No, because both linear and angular momentums are changed by each tap done by the guy. Those changes are the same magnitude whether or not the devices are spinning or not.

do you agree there is a difference in the system response to the impulse as I described it?

Yes. One tumbles due to the change in angular momentum, and the other wobbles due to the same change in angular momentum.  I do not agree that the changes in momentum are any different given identical input taps.

[Bored chemist]

If all is well balanced (ideal) then the discs will spin inside and the structure of CD players stays as is.

Would you like a second guess?

It's related to this bit

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

[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. Below is an article from the NSF in 2004 after the first wave of dust settled and the status quo fought off a threat to their livelihood. This was attempt two, which by lack of mention in this discussion was also bottled away by the science swamp.

https://nsf.gov/discoveries/disc_summ.jsp?cntn_id=100044&org=NSF

The implications of the core rotating faster than the crust, is the earth's surface rotation may well be  driven by the core, through visco-plastic friction. This outer core friction should also be producing heat, which then flows into the outer core and lower mantle, which is being convect toward the surface. It is a global warming wild card.

If we accept this data as true, then we need to revise the earth sciences since no models anticipated this, nor do many take it into account. We have a moon sized object, inside the earth, rotating faster than the surface. This is a very dominate earth feature, that cannot be ignored by any theory that claims to be valid.

I have pondered this and the wild card variable appears to be water. Water is continuous from the atmosphere, to the oceans, through the crust, into the mantle and theoretically to the core. The water placement is not driven by gravity, old asteroids, and density differences, but by chemical potential based on enhanced phase solubility at various conditions. As water gets hotter and higher in pressure it gets increasingly aggressive to minerals inside the earth. This is accelerated by the second law of entropy.

Experiments with extreme pressure and temperature water; at US National Labs, show new phases of water that appear to correspond to the layering within the earth; atmosphere is water vapor, oceans are liquid water, inner crust=hydrothermal water, upper mantle=superionic water, lower mantle=ionic water, outer core and core=metallic water. The phases of water define the layers of the outer and inner earth.

This layering of water would imply that the ionic water near the outer core; O-2, H+, is rusting the iron core and extracting energy and electrons. This driven by the sun evaporating the surface water and the continuity of water to the core. The movement of positive charge upward by solar evaporation causes a potential for electrons to move upward. Along with this electron movement are other sources of deep ocean heat.

The maximum solar heating occurs along the equator, which has more material; bulge. This is the main source and vectors for electrons This east-west, helps too direct the north-south magnetic field.

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?

[Bored chemist]

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.

[Jaaanosik]

If all is well balanced (ideal) then the discs will spin inside and the structure of CD players stays as is.

Would you like a second guess?

It's related to this bit

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

What happens when 3 torque pseudovectors of different direction meet in one point and the magnitude is the same?
The 3 pseudovectors need to form a plane. The arrangement is possible.
For the 3d space 4 torque pseudovectors are required. The ISS uses 4 CMGs.

[Bored chemist]

They add together to form a single (pseudo) vector.
Which is the same as

taping them together with the axes aligned

Except that the magnitude is smaller.
If you stacked the CD players like coins then you could get three times as much angular momentum  as just one.
With the 3 at right angles they give a vector sum of (I think) root 3 along the diagonal of the cube


So, anyway, you forgot to answer this bit

Anyay, you are missing the point, and I suspect it's deliberate.

Imagine that the CD player has an IR remote control and is running on batteries.

You set it in front of you in zero G then, using the remote control, you press "play".

What happens?

[Bored chemist]

The 3 pseudovectors need to form a plane.

That's about the one thing that three orthogonal vectors can't possibly do.

[Jaaanosik]

The 3 pseudovectors need to form a plane.

That's about the one thing that three orthogonal vectors can't possibly do.

When you asked the question I said "well balanced (ideal)".
That means the CD players would be in 3 planes of the triangular prism with 60 degree angles, axes forming a plane.
The better solution is 4 CMGs (CD players) at tetrahedron vertex corners (or planes/faces) formed by equilateral triangles.
The 4 axes would point to the center of the tetrahedron.

So we turn on CD players of an ideal setup, what happens?

[Bored chemist]

Well, four CD players forming a tetrahedron would be even funnier.


But I would still like you to answer the question you keep ignoring.

So, anyway, you forgot to answer this bit

Quote from: Bored chemist on Yesterday at 17:47:20
Anyay, you are missing the point, and I suspect it's deliberate.

Imagine that the CD player has an IR remote control and is running on batteries.

You set it in front of you in zero G then, using the remote control, you press "play".

What happens?

[Jaaanosik]

Well, four CD players forming a tetrahedron would be even funnier.


But I would still like you to answer the question you keep ignoring.

So, anyway, you forgot to answer this bit

Quote from: Bored chemist on Yesterday at 17:47:20
Anyay, you are missing the point, and I suspect it's deliberate.

Imagine that the CD player has an IR remote control and is running on batteries.

You set it in front of you in zero G then, using the remote control, you press "play".

What happens?

I answered in the post #333.

[Halc]

But I would still like you to answer the question you keep ignoring.

He did indeed answer the question, albeit a very wrong one.  Jano apparently has no clue how to do vector arithmetic. Lacking his literacy in the language of mathematics, I'm not bothering to continue. Have fun.

Some errors:
His 4-CD tetrahedron would have zero net angular momentum and would thus exhibit zero gyroscopic effects.
No pair of sides of a regular tetrahedron meet at a 60° angle, nor do the axes passing through their centers.
The angle (called a dihedral angle) is about 70.5°.

[Jaaanosik]

But I would still like you to answer the question you keep ignoring.

He did indeed answer the question, albeit a very wrong one.  Jano apparently has no clue how to do vector arithmetic. Lacking his literacy in the language of mathematics, I'm not bothering to continue. Have fun.

Some errors:
His 4-CD tetrahedron would have zero net angular momentum and would thus exhibit zero gyroscopic effects.
No pair of sides of a regular tetrahedron meet at a 60° angle, nor do the axes passing through their centers.
The angle (called a dihedral angle) is about 70.5°.

60 degrees was for the triangular prism, 3 CD players, not the tetrahedron and the 4 CD players.
I did not talk about any angles in regards to the tetrahedron.

[Halc]

60 degrees was for the triangular prism, 3 CD players, not the tetrahedron and the 4 CD players.
I did not talk about any angles in regards to the tetrahedron.

My apologies: You did say prism. My mistake there. What's the point of arranging them in that pattern? Why do you think the guy in the video didn't choose to do that? Why is something with no angular momentum 'ideal'? What benefit do you expect from it, or from the tetrahedral arrangement?  You'd not be able to tell if they were running or not in either case. Might as well just tape three decks of cards together in a prism arrangement.

OK, I made a second mistake in reading what you said. You didn't answer BC's question in post 333 since it is preceded by 'if ideal', which apparently means a different arrangement than the 1-CD or 3-orthogonal cases that he was asking about. So you answered a different question. My apologies to BC this time for that mis-read.

[Bored chemist]

I answered in the post #333.

No, you did not.
I was talking about just one single CD player.
You were talking about more than one.

the discs will spin inside and the structure of CD players

No please stop trying to evade the question.

But I would still like you to answer the question you keep ignoring.
Quote from: Bored chemist on Yesterday at 21:08:17
So, anyway, you forgot to answer this bit

Quote from: Bored chemist on Yesterday at 17:47:20
Anyay, you are missing the point, and I suspect it's deliberate.

Imagine that the CD player has an IR remote control and is running on batteries.

You set it in front of you in zero G then, using the remote control, you press "play".

What happens?

[Bored chemist]

I imagine it will take ages to get a sensible answer to this from Jaaanosik , but it's an interesting question so here goes.

Jaaanosik
Imagine that I got a huge number of CD players- a few cubic metres of them.
And I arranged them randomly in a big rigid box.
They are packed in the box so they can't move with respect to each other.

What happens when I press the remote and set them all spinning?  (I'm ignoring the practicality that the one sin the middle will overheat).

From what you have acid before I think you will say that the combination will act like a gyroscope because all the angular momenta of the disks will act together.
Have I understood you correctly?

[Jaaanosik]

I answered in the post #333.

No, you did not.
I was talking about just one single CD player.
You were talking about more than one.

the discs will spin inside and the structure of CD players

No please stop trying to evade the question.

But I would still like you to answer the question you keep ignoring.
Quote from: Bored chemist on Yesterday at 21:08:17
So, anyway, you forgot to answer this bit

Quote from: Bored chemist on Yesterday at 17:47:20
Anyay, you are missing the point, and I suspect it's deliberate.

Imagine that the CD player has an IR remote control and is running on batteries.

You set it in front of you in zero G then, using the remote control, you press "play".

What happens?

When you said:
"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?"
I replied with what I said to point out there is a difference based on the arrangement of the CD players.

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

[Bored chemist]

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?

[Jaaanosik]

60 degrees was for the triangular prism, 3 CD players, not the tetrahedron and the 4 CD players.
I did not talk about any angles in regards to the tetrahedron.

My apologies: You did say prism. My mistake there. What's the point of arranging them in that pattern? Why do you think the guy in the video didn't choose to do that? Why is something with no angular momentum 'ideal'? What benefit do you expect from it, or from the tetrahedral arrangement?  You'd not be able to tell if they were running or not in either case. Might as well just tape three decks of cards together in a prism arrangement.

OK, I made a second mistake in reading what you said. You didn't answer BC's question in post 333 since it is preceded by 'if ideal', which apparently means a different arrangement than the 1-CD or 3-orthogonal cases that he was asking about. So you answered a different question. My apologies to BC this time for that mis-read.

The most intuitive explanation without going into detail is the axes do not meet at the center of the mass for the 3 CD players system built as in the video.
The tetrahedron the axes meet at the center of the mass.

[Bored chemist]

The simplest system where the overall angular momentum is zero would be two players stuck together "feet to feet".

Tetrahedra, prisms etc just add to the complexity.

Do you think that a pair of players stuck together in this way would have any gyroscopic effect?
If you pushed them would they tumble or wobble?