Re: Calculating Newtons in Joules and Joules/s


Dennis B wrote:
Randy Poe wrote:
The static pressure of a fluid, such as the compressed air inside of a
tank of compressed air, is considered potential energy although the
pressure is due to the kinetic energy of molecular thermal vibrations.

Hmmm. If you have a reference for that, I'd be interested.

I'm willing to concede that in this instance, treating a
compressed gas like a spring, with the KE of the molecules
causing pressure represented as a PE, giving rise to a
force -- is a reasonable thing to do.

However, pressure is due to collisions of molecules
with the container and with each other. It isn't due
to vibrations.

I note that on this subject you sound semi-knowledgeable
and rational. It's very different from your attempts to
equate force, momentum, and energy in "new physics".

Likewise, electrical potential is due to the pressure of electrons
repelling each other.

There is a derivative relationship between forces
and potential. Your sentence contains some truth.
Unlike in your first example, none of the energy in
this situation is kinetic.

Furthermore, heat tends to raise the electron energy levels,
thus increasing the electrical potential of atoms.

Temporarily, and that is indeed a form of PE.

Yet, those electrons are moving, are they not?

No.

You're saying that those electrons are not orbitting the atoms and that
the atoms which the electrons are asociated with are not vibrating,

Right. That model was discarded nearly a century ago.

thus causing the electron to move (with the atom) as well? Then how do
you explain the infra-red radiation which is associated with heat?

Energy is emitted in discrete packets called quanta. The
minimum energy packet has energy hf, where hf is
the frequency. When a particle changes energy
states in a jump from E1 to E2, it emits a photon of
energy (E2-E1) and frequency (E2-E1)/h.

What is there about this that implies electrons are little
planets to you?

Is
it not the product of the thermal vibration of atoms (as in a quartz
heater which drives a piezo-electric quartz crystal at infra-red
frequencies)?

No, it is not the result of something wiggling at frequency f.
It is the result of an energy change equal to hf.

And isn't such thermal vibration of atoms and molecules
what gives rise to the pressure of a fluid?

No, I don't think that's what gives rise to the pressure
of a fluid. If you are talking about why pressure increases
with depth, that is due to static gravitational mass of
the fluid. If you are asking what gives rise to the
pressure of a gas as you compress it, it is the KE
of travel of the molecules.

Furthermore, potentials can be comprised of
opposing forces, which cancel so as to create zero net force.

No.

What about a mass balanced on a scale?

What about it? You said someting about "potentials
comprised of opposing forces". There's nothing in that
balance give rise to a potential.

The force of gravity pulls it
down. Yet, the scale pushes up. The net force is zero, since there is
no acceleration, yet there are forces acting on the masses.

Yes, such a mass is experiencing a balance of forces. What
does that have to due with your statement about "potentials
can be comprised of opposing forces"? Potentials aren't
comprised of forces, opposing or otherwise.

- Randy

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