Problem in understanding how upwards acceleration works (General Relativity)

[Mike_bb]

There certainly are deformations (Hooke’s law). However, if the deformations are the explanation for the acceleration then you are left with a pretty big problem. You can put an accelerometer on rubber or on steel. Both accelerometers read the same acceleration, but the deformation of the rubber is much more since it is less stiff.

The support thrust up the body. This is infinitesimally small displacement upward. Sum of such displacements (integral) is result displacement of the body.

 

[Dale]

The support thrust up the body. This is infinitesimally small displacement upward. Sum of such displacements (integral) is result displacement of the body.

Then why doesn’t rubber have a larger proper acceleration than steel? The deformations in rubber are larger (Hooke’s law), the integral is larger too. So if the deformations cause the acceleration then the acceleration of the rubber should be larger.

 

[Mike_bb]

Then why doesn’t rubber have a larger proper acceleration than steel? The deformations in rubber are larger, the integral is larger too. So if the deformations cause the acceleration then the acceleration of the rubber should be larger.

In the previous post I wrote about infinitesimally small displacements not deformations.

 

[Dale]

In the previous post I wrote about infinitesimally small displacements not deformations.

In the steady state there is no displacement in the ground frame, there is deformation in all frames.

 

[Mike_bb]

In the steady state there is no displacement in the ground frame, there is deformation in all frames.

In explanation it's written that the body on the support is not at absolute rest.

 

[Mike_bb]

In the steady state there is no displacement in the ground frame, there is deformation in all frames.

I found another explanation. It's written about infinitesimally small displacement $dx$ that is caused by support.

 

[Dale]

In explanation it's written that the body on the support is not at absolute rest.

It doesn’t matter if it is at absolute rest (whatever that means). It is at rest in the ground frame.

More importantly, you can always use the accelerometer’s frame where the accelerometer is always at rest by definition.

I found another explanation. It's written about infinitesimally small displacement $dx$ that is caused by support.

There is deformation. There is not displacement.

 

[Mike_bb]

There is deformation. There is not displacement.

There was:

If we consider the infinitesimal displacement of a body under the action of the support reaction force over an infinitesimal time interval $dt$, this displacement is precisely due to the body's proper acceleration.

 

[Dale]

If we consider the infinitesimal displacement of a body under the action of the support reaction force over an infinitesimal time interval dt, this displacement is precisely due to the body's proper acceleration.

That is wrong in the ground frame. Is that a quote from an AI? It sounds like something that an AI would say.

The displacement is zero in the ground frame.

 

[Mike_bb]

Dale, big thanks!! I just got an insight into how it works!

 

[Dale]

Dale, big thanks!! I just got an insight into how it works!

I am glad. I think that I should recommend that you begin studying physics from a good textbook. So far, asking AI and asking us seems to be making some unnecessary challenges for you. It may be better to learn from a textbook that is well structured with exercises that you can practice to understand. Then our role can be to help fill in any small gaps that the textbook leaves. (AI is only useful if you already understand the physics and can recognize when it is wrong)

 

[Mike_bb]

Dale,

Reading the textbooks is good practice but communication with scientists is the best practice.
Mind ignites mind. (Johann Wolfgang von Goethe)

 

[Sagittarius A-Star]

Dale,
Reading the textbooks is good practice but communication with scientists is the best practice.

No. Both, plus calculating to solve problems, are needed for successful lerning.

 

[Nugatory]

Reading the textbooks is good practice but communication with scientists is the best practice.
Mind ignites mind. (Johann Wolfgang von Goethe)

Goethe (actually not Goethe, that’s a loose paraphrase from an English language translation) has a good point but you’ve misunderstood it.

Skipping the textbooks leaves you without a solid foundation for communicating with specialists. You may be getting something out of your experience here, but it is far less than if you were to invest in that foundation as well.