Re: The Inertia of Stress (Attn: Tom Roberts)

On 11 ago, 07:01, "Pmb" <some...@xxxxxxxxxxxxx> wrote:
<va...@xxxxxxxxxxx> wrote in message

news:1186675897.577998.202300@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxx





On 9 ago, 05:49, "Pmb" <some...@xxxxxxxxxxxxx> wrote:
Hi Tom and everyone

In a previous thread I mentioned the inertia of stress. I recently came
across an article on just this topic. Its called

Tom - Please correct me if I'm wrong but to my recollection this was a
something you weren't aware of. I.e. I had posted the comment

It is a fact that after Einstein's 1905 work he continued on to
complete
his
study of the mass-energy relation. He made one important discovery and
that
was that relativistic mass (and also rest mass) was a function of
stress.

and you responded with

This is the first I have ever seen anyone claim that.

Einstein's work on this suvbject, i.e. what led to the inertia of stress,
was in his paper called "On the Inertia of Energy Required by the
Relativity
Principle," A. Einstein, [Annalen der Physik 23 (1907): 371-384]. The
particular section is called "On the kinetic energy of a rigid body in
uniform translation subject to external forces."

The title of the section confuse us. How a body subject to external
forces can be moving in uniform translation? Because the resultant of
the external forces is zero.

Because the total force is zero. E.g. Consider a block at rest in the
inertial frame S. In S forces are applied to opposing sides of equal and
opposite magnitude. Therefore the block will at all times be a rest or
uniform motion. For details please see -http://www.geocities.com/physics_world/sr/inertial_energy_vs_mass.htm

This link doesn't function to me (maybe it has an error).
And what can provoke such set of forces in a rigid body?

Take the box and squeeze it between for forefinger and thumb. Einstein use
electric forces which resulted from the body being immersed in an E-Field.
The box has charges of opposite side but opposite magnitude of the ends.

I see it in another way. You can read in the 1907 paper {the body is
rigidly electrified (with continuously distributed electricity)}. In
1907 an electrified body has single sign charges in all its surface.
The atomic-molecular model was in full use a little later (remember
that atom model with positive small nucleus and negative envelope was
1913). In 1907 we have an external field (of an unknown distribution)
stressing an electrified (single sign) body (of an unknown form), in
2006 we have a thin disk with different sign charges in its faces
stressing (compressing) it. What I see in common here is an
interchange between electrical and elastic potential energies, no
matter if an internal electric structure is supposed for the body or
not.
Evidently...stress (in other section of the same paper
Einstein convinces us that a signal propagates for the rigid body with
less than c velocity, couldn't be then so rigid).

Correct. Did I send you that paper?

Yes, you did it. I was squashing my head in it for several days...until
you sent me the 2006 Rodrigo Medina's paper and all light was on over
me in a single instant!
And what has a
stressed body? Elastic potential energy. And what measures energy? ...
Mass.

You'll find that in this example that is an incorrect assumption. Rindler
noted that E = mc^2 is not a general expression but holds only in certain
cases. Particle physicists all work with the same special case, a charged
particle in an EM field ... or at least that is my understanding of what is
actually measurable is the path taken by the charge which is made visual
through a bubble chamber or something simpler

I haven't access to Rindler's paper yet. I know that particle
physicists always work with free particles (that in my view have
already its maximal potential energy-rest mass value). In the
accelerators always an external energy is added to the particle
increasing its velocity and corresponding kinetic energy-mass
(potential energy- rest mass remains in its maximal constant value).
When a bounded particle increases its velocity using its own potential
energy (its field energy), its total energy-mass remains constant
(only a potential energy-rest mass interchange with kinetic energy-
dynamic mass takes place).
I consider particle-antiparticle converting in photons and vice versa
a direct experimental evidence in favour of my view. All the maximal
potential energy-rest mass of the particles at rest infinite separated
converting in the same maximal kinetic energy-dynamic mass quantity
(and vice versa). Those extremes are simply particular cases, all the
time the total mass-energy is conserved and rest mass measures always
potential energy. You can add here an external added kinetic energy-
dynamic mass to the particles without any limit (the usual practice in
accelerators).




And what other thing measures mass?...Inertia. The inertia of
stress had born!
There is also an article in Am. J. Phys. from last year on this subject.
I
only recently obtained a copy of it. Its similar to Rindler and Denur's
"paradox" paper regarding a capacitor but this one gets into it more
deeply

"The inertia of stress," Rodrigo Medina, Am. J. Phys. 74(11), November
2006

Thanks to Peter I read already the paper.
The abstract reads
-------------------------------------------
We present a simple example in which the importance of the inertial
effects
is evident. The system is an insulating solid narrow disk whose faces are
uniformly charged with equal charges of equal magnitude and opposite
signs.
The motion of the system in two different directions is considered. It is
shown how the contribution of energy and momentum of the stress that
develops inside the solid to balance the electromagnetic forces have to
be
added to the electromagnetic contributions to obtain the results
predicted
by the relativistic equivalence of mass and energy.
-------------------------------------------
As Einstein in his paper, Medina put electric charges in the body
surface, a thin insulated disk, positive in one face and negative in
the other (Einstein put a single type of electrical charge interacting
with an external field, much difficult to understand than Medinas's
case).
I e-mailed a copy of this to you.

Don't fail reading it, Roberts! I can advance you that this topic is
related with 1905 Relativity addressing gravitation.

Tom should read this I agree. At least so he can't say that he never heard
of this before.

I am a little surprised about the almost total absence of contributors
to this post until now (included, of course, Tom Roberts one). No one
interested in "the inertia of stress"? Let me use this occasion to
give you (and all interested readers) two links about the mass of
potential energy:
http://www.pubmedcentral.nih.gov/picrender.fcgi?artid=336961&blobtype...
THE ACTUAL MASS OF POTENTIAL ENERGY, A CORRECTION TO CLASSICAL
RELATIVITY
L. Brillouin
Proc Natl Acad Sci U S A. 1965 March; 53(3): 475-482.
http://www.pubmedcentral.nih.gov/picrender.fcgi?artid=219831&blobtype...
THE ACTUAL MASS OF POTENTIAL ENERGY, II
L. Brillouin
Proc Natl Acad Sci U S A. 1965 June; 53(6): 1280-1284.

RVHG (Rafael Valls Hidalgo-Gato)

Pete- Ocultar texto de la cita -

- Mostrar texto de la cita -- Ocultar texto de la cita -

- Mostrar texto de la cita -

.

Relevant Pages

  • Re: 1905 Relativity is sufficient to support GPS function
    ... >>> I have to think in that way is that the relativistic mass concept was ... energy of classical gravity is not zero at large distances. ... > of kinetic and potential energy is taking place. ... >> absence of an additive constant. ...
    (sci.physics.relativity)
  • Re: 1905 Relativity is sufficient to support GPS function
    ... >> I am not saying that the relativistic mass concept is in common use ... relationship between mass and energy. ... field has zero potential energy as a physical fact is simply a detail ... >>> absence of an additive constant. ...
    (sci.physics.relativity)
  • Re: "Dimensional Analysis and Relativity"
    ... No force is necessary to cause orbital motion. ... Every orbiting mass m has kinetic and potential energy due to its ...
    (sci.physics)
  • Re: Is Lorentz contraction a real process
    ... > to the lower energy one n'. ... > The really important point here is the rest mass measuring potential ... > referring to total energy being equal to potential energy plus kinetic ...
    (sci.physics.relativity)
  • Re: Rest mass
    ... recognizing that rest mass measures ... potential energy, fixing an absolute zero point where rest mass ...
    (sci.physics.relativity)
Loading