Re: Orbital precession w/o GR

On Fri, 30 Nov 2007 01:27:56 -0000, "JMA" <NOSPAM@xxxxxxxxx> wrote:


"Eric Gisse" <jowr.pi.nospam@xxxxxxxxxxxxxxxx> escreveu na mensagem
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On Thu, 29 Nov 2007 16:13:05 -0000, "JMA" <NOSPAM@xxxxxxxxx> wrote:


"bz" <bz+spr@xxxxxxxxxxxxxxxxxxxx> escreveu na mensagem
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"JMA" <NOSPAM@xxxxxxxxx> wrote in
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What is really a mystery is how people talk about
precession of mercury orbit, but nobody has any idea
what precession is

[quote http://www.thefreedictionary.com/precession]
1. The rotational motion of the axis of a spinning body, such as the
wobbling of a spinning top, caused by torque applied to the body along
its
axis of rotation.
2. The motion of this kind made by the Earth's axis, caused mainly by
the
gravitational pull of the Sun, Moon, and other planets. The precession
of
Earth's axis has a period of nearly 25,800 years, during which time the
reference points on the equatorial coordinate system (the celestial
poles
and celestial equator) will gradually shift their positions on the
celestial sphere. The precession of the equinoxes is the slow westward
shift of the autumnal and vernal equinoxes along the ecliptic, resulting
from precession of the Earth's axis. See also nutation.
[unquote]

For instance:
A 3 years old kid knows very well what light is.
But a 3 years old kid knows nothing about what light really is and
how he can be fooled by light.

Some facts about precession:
1 - Constant precession requires constant torque.

No, it does not. Study rigid body motion.

Funny, it is you that needs to study rigid body motion.

Yaaaaawn.

I have gone through the rigid body mechanics sections of both
Goldstein and Symon. You still don't know what you are talking about.


Look here, let:
Precession angular velocity be (omega)p
Torque be T
Main angular velocity be (omega)3
Inertia moment along the main spin axis of the rigid body be I3.

Then,
(omega)p = T / (I3(omega)3)

Since I3 and (omega)3 are constants, even a 10 year kid
will see that when torque changes the angular precession
velocity changes too.

Wrong as usual. Time for you to open a classical mechanics textbook...

The body axes are NOT the same as the axes in which a body precesses,
rotates, and nutates.



Where is the constant torque? The torque is highly variable.

Strawman, and the argument is motivated from classical mechanics.

You always dance with rotation of the rigid body.

Why do you continue to think you know what you are talking about when
two textbooks on classical mechanics explicitly disagree with you?



2 - Where does the kinetic energy come from?

I believe kinetic energy comes from the kinetic energy fairy.

Since energy maust be conserved, please tell me where
the precession kinetic energy comes from.

Why do you continue to harp on the "WHERE DOES THE ENERGY COME FROM?"
thing?



The kinetic energy comes from the potential energy.

Nope. The sum is conserved and there is an interchange of the two but
that does not mean one comes from the other.

What a moron.
The energy conservation Law requires that the sum is conserved.

I can prove this - can you?

(always at any instant) and this repeats over and over around
all the physics.

You have kinetic energy involved (increasing) and no other
source for energy then potential.

Whenever you want to talk physics you show the bluff you are.

Tried it before - you didn't understand. My study of classical
mechanics has continued - have you looked at Symon or Goldstein yet,
or do you still think you don't need to look at a book?

You probably still don't understand how to properly construct a
Lagrangian for a system.


Come on, let me laugh more on you and tell me where the
precession kinetic energy comes from.

Kinetic energy fairy.



Since energy is conserved, potential energy needs to be
dissipated. That is, a smaller secondary motion, called
nutation, occurs.


If you knew that planets orbit in a plane and understood what nutation
is you would see why what you said was really, really stupid.

Nutation is the motion orthogonal to precession and both of
them orthogonal to the main spin axis.
I bet you going to say, no it isn't !
(plus the usual crap, learn ... bla-bla.)

Actually that is correct. Now explain to me how a planet nutates even
though it moves in a plane.


For you nutuation is only a sound word.
Tell me something more about nutation.

.

Relevant Pages

  • Re: Orbital precession w/o GR
    ... precession of mercury orbit, ... The rotational motion of the axis of a spinning body, ... it is you that needs to study rigid body motion. ... I believe kinetic energy comes from the kinetic energy fairy. ...
    (sci.physics.relativity)
  • Re: Orbital precession w/o GR
    ... precession of mercury orbit, ... The rotational motion of the axis of a spinning body, ... The motion of this kind made by the Earth's axis, ... I believe kinetic energy comes from the kinetic energy fairy. ...
    (sci.physics.relativity)
  • Re: Orbital precession w/o GR
    ... precession of mercury orbit, ... The rotational motion of the axis of a spinning body, ... The motion of this kind made by the Earth's axis, ... I believe kinetic energy comes from the kinetic energy fairy. ...
    (sci.physics.relativity)
  • Re: Orbital precession w/o GR
    ... precession of mercury orbit, ... The rotational motion of the axis of a spinning body, ... The motion of this kind made by the Earth's axis, ...
    (sci.physics.relativity)
  • Re: Reason for Procession of the Equinox?
    ... > precession itself. ... That is a slight clockwise motion of the top's axis. ... that spin interacts with the direction of gravity's pull. ... over to the Earth and the Moon. ...
    (sci.astro.amateur)