Luigi Fortunati il 21/03/2024 17:13:41 ha scritto:
> What makes gravitational forces different from non-gravitational forces?
>
> Luigi Fortunati
>
> [[Mod. note -- That's a very good question!
>
> That is, the gravitationalforce on a body with inertial mass 2 kg is (a) precisely twice that on a body with inertial mass 1 kg, and (b) the *same* independent of the composition of the body.
> -- jt]]

It is certainly true the (b) which makes gravitational forces different
from non-gravitational ones.

But (if I'm not mistaken) (a) also applies to the electromagnetic force
which, on a 2 gram body of any material X, is exactly double that on a 1
gram body of material X.

Is that so?

Luigi Fortunati

On 3/24/24 3:29 PM, Luigi Fortunati wrote:
>> [Moderator] That is, the gravitational force on a body with
>> inertial mass 2 kg is (a) precisely twice that on a body with
>> inertial mass 1 kg,
>
> But (if I'm not mistaken) (a) also applies to the electromagnetic
> force which, on a 2-gram body of any material, is exactly double
> that on a 1-gram body of any material. Is that so?

Not at all! -- If one is charged and one is not, the electromagnetic
forces on them will be VERY different.

I repeat: your approach of making false statements here and expecting to
be corrected is not working, and you are CLEARLY not learning much
physics, if any. You NEED to get some good textbooks and STUDY. Better
yet, enroll in a college or university physics course, so you will have
an instructor with whom you can discuss your many misconceptions and
confusions.

Tom Roberts

Luigi Fortunati il 24/03/2024 07:29:00 ha scritto:
> [[Mod. note -- Perhaps.
>
> That is, let's call your 1-gram body "A", and your 2-gram body "B".
> We can think of B as a pair of one-gram halves (call them "B1" and "B2")
> glued together. The question is, does the presence of B1 change the
> electromagnetic (EM) field at B2's location, or vice versa, by an
> amount large enough that we need to care about it? If *not*,
> then the EM force acting on B will be the sum of
> (a) the EM force acting on B1 alone (i.e., if B2 were NOT there), and
> (b) the EM force acting on B2 alone (i.e., if B1 were NOT there).
> Assuming that B is small enough that the EM field doesn't vary
> significantly across B's diameter, we should have (a) = (b), so in
> this case the EM force acting on B should be twice the EM force
> acting on A.
>
> But, if the presence of B1 *does* change the EM field at B2's location
> by a significant amount, then the EM force acting on B will *not*
> equal the sum of (a) and (b) above, and the EM force acting on B will
> *not* be twice the EM force acting on A.

This thing you say also applies to the gravitational field: if the presence of B1 changes the gravitational field at the position of B2 by a significant amount, then the gravitational force acting on B is not equal to the sum of (a) and (b ) and the gravitational force acting on B is not double the gravitational force acting on A.

The proportionality between force (whether gravitational or EM) and mass depends on each individual particle because it is precisely the particle that intercepts its share of the field force (whether gravitational or EM).

Obviously (and to avoid any misunderstanding) the comparison must be made between equal materials and, that is, if the material of the first body is XYZ, that of the second body is also XYZ (if the material of the first is iron, that of the second is also iron , if one is wood the other is also wood).

Luigi Fortunati

Luigi Fortunati wrote:

> The elevator in free fall in the gravitational field is an inertial
> reference system.

> Is the elevator in free fall in the magnetic or electric field also an
> inertial reference system?

> Luigi Fortunati

That will depend upon the corresponding momentum of the gravitons
involved in the free fall. The fabric of spacetime will bend accordingly,
to account for the apparent distortions to the so-called magnetic and
electric fields.

bt

[[Mod. note -- We don't need the concept of "graviton" here -- a
classical picture is fine.
-- jt]]