B Rotation is absolute, linear motion is relative?

[Ibix]

You mean if friction is zero between water and bucket walls, water will contiue to spin for some time after G room is stoped, for right case?

I mean in general. You'll note A.T.'s analysis explicitly talks about "lag" and "tending to" his solution.

 

[A.T.]

why would one frame be more true then other...

As for the why-part: We don't really know. Mach's principle is the idea that inertial frames are related to the large-scale distribution of matter in the universe.

 

[vanhees71]

Mach's principle seems to be vague enough that obviously people still today argue about, whether general relativity is "Machian". I don't think so, because GR is based on strict locality, i.e., all observations are defined as local observations, and all there is left from Newton's Lex I, still valid within special relativity, is that in any spacetime point there exist local inertial frames of reference, i.e., Poincare symmetry is a local gauge symmetry. The gauge group of GR is general (local) diffeomorphism invariance (aka "general covariance").

In our present universe, according to the "cosmological standard model" we have, on large-scale course grained average, a maximally symmetric FLRW spacetime geometry, according to which the physically distinguished local inertial frames are given by the rest frame of the cosmic microwave background raditation at any point in spacetime.

 

[John Mcrain]

@A.T.

Lets say we connect turntable(with frictionless bearings) at the bucket bottom.

1.If we set this bucket at center of G-room, bucket will not rotate,because friction is zero.

2.If we set this bucket close to wall of G-room,after we stop rotation of G-room,will be bucket rotate?
When G-room is rotating, bucket is free to spin due to friction less bearings, will bucket resist to spin in relation to ground frame(dont change orinetation) or it will resist to spin in relation to G-room(keep same face toward center of G-room)?

 

[A.T.]

@A.T.

Lets say we connect turntable(with frictionless bearings) at the bucket bottom.

1.If we set this bucket at center of G-room, bucket will not rotate,because friction is zero.

2.If we set this bucket close to wall of G-room,after we stop rotation of G-room,will be bucket rotate?
When G-room is rotating, bucket is free to spin due to friction less bearings, will bucket resist to spin in relation to ground frame(dont change orinetation) or it will resist to spin in relation to G-room(keep same face toward center of G-room)?

Is it just an empty bucket? If the bearing is such that no moments can be applied to the bucket, its angular momentum will remain constant in inertial frames.

 

[John Mcrain]

Is it just an empty bucket? If the bearing is such that no moments can be applied to the bucket, its angular momentum will remain constant in inertial frames.

So during rotation of G-room, bucket will keep same orientation in relation to ground(inertail,stationary frame), but it will rotate in relation to G-room(rotating frame). So this is basicaly same case as my "right case".
When I draw my "right case", I was thinking that bucket to keep same orientation to ground it will need some mechanics/gears to allow this movememt, but it turn out it is enough to put bucket on turntable with frictionless bearings and inertia will do rest of job.
Problem is I didnt know if bucekt will resist to spin in relation to ground or to G-room.
Why you ask if is bucket empty?

 

[A.T.]

the physically distinguished local inertial frames are given by the rest frame of the cosmic microwave background raditation at any point in spacetime.

Just like we receive CMB that was emitted by matter which is now very far away, we might also be affected by this matter in terms of inertia.

But this seems impossible to test and either way doesn't change much about out local physics.

 

[A.T.]

So during rotation of G-room, bucket will keep same orientation in relation to ground(inertail,stationary frame), but it will rotate in relation to G-room(rotating frame). So this is basicaly same case as my "right case".

If an empty bucket starts at rest in the ground frame, and is mounted on a vertical friction-less axis though its CoM, yes.

Why you ask if is bucket empty?

Because water will complicate things, It can move relative to the bucket and thus shift the CoM.

 

[vanhees71]

Just like we receive CMB that was emitted by matter which is now very far away, we might also be affected by this matter in terms of inertia.

But this seems impossible to test and either way doesn't change much about out local physics.

the CMB is the remnant of electromagnetic thermal radiation within the soup of hot and dense charged matter, which was very close to thermal equilibrium, in the early universe. It decoupled from the matter about 400'000 years after the big bang when atoms were formed and matter got electrically neutral.

 

[John Mcrain]

@A.T.
How do you know all this without experiments?

I need to take my kitchen turntable to find answers,I was so happy when stoped turntable and water spins inside glass (left case)!

 

[jbriggs444]

How do you know all this without experiments?

It's Newtonian mechanics, not rocket science. It works quite well. Conservation of angular momentum is well confirmed experimentally. Galileo did a lot of the experimental work.

 

[vanhees71]

Rocket science is a great deal also Newtonian mechanics ;-).

 

[John Mcrain]

It's Newtonian mechanics, not rocket science. It works quite well. Conservation of angular momentum is well confirmed experimentally. Galileo did a lot of the experimental work.

What physics field is consider the hardiest? Does this frames questions what we are talking here is valid in micro world, atom and smaller particels?

 

[John Mcrain]

Even I never study physics or math, I feel stupid when I see that my questions are so easy and trivial for you here...

 

[berkeman]

Even I never study physics or math, I feel stupid when I see that my questions are so easy and trivial for you here...

You should not feel stupid. Instead, enjoy the learning and keep asking questions. We all had to learn this stuff sometime...