About precession

Precession of the Earth is, where I've seen it (see the .pdf link), being presented as a torque
working on Earth periferal bulge eqvivalent to a gravitational pull in a spinning gyroscope resting
it's end in a pivot.
Isn't that in error?

I've posted in sci.geo.geology as part of another point, but it's not been archived yet, so I copy:

snip

The principal axis is the Earth own spin-axis. If the Earth responds to it's present inertia and
periferal bulge relative to the sun - without spinning itself - it would have it's primary axis
plunging into
the plane of it's orbit around the Sun (tilt = 90 degrees).

The magic of a gyroscope is not that it precesses around it's pivot, but that it's free-flowing (if
you rest it horizontally on the edge of your table) - resisting the torque induced from gravity.
This free-flight is (imo) expressed in the Earth/Sun system as the Earth axis does not plunge down
into the plane of the ecplise.

The torque-vector working on Earth' periferal bulge is everywhere lying in the ecliptic and is
perpendicular to the two bodies (aligned along it's axis of revolution (=Earth's center)) - it's
oriented as a tangent to Earth orbit. .... But it's occilating through the year, or having uppersit
directions on each side of the Sun. Looking at torque as a kind of work, and angular momentum as the
accumulated work over time ... it doesn't look as if the influence of the torque on Earth will add
up to anything due to the occilation and change of sign!
The gyroscope, on the other hand, accumulates a precession becourse the gravitational torque doesn't
change direction (or sign) - it's continuously oriented as a tangent to the line between the center
of the gyroscope and it's pivot (the edge of the table, perpendicular to the spinning gyroscopes own
direction of angular moment (L, along the spinaxis)) - and merely moves this vector (L) in a slow
circular motion.

In other words: the observed precession is not due to the Sun's differential pull in the periferal
bulge in the manner I have presented.
What am I doing wrong?

This link points to the same logical weakness (the occilation that cancels out) and propose Earth
precession as eqvivalent to
'Regression of the nodes of the Moon'

http://mb-soft.com/public/precess.html

In this presentation:

http://orca.phys.uvic.ca/~tatum/celmechs/celm6.pdf

it's obvious that the precession is calculated from the same formulas that applies to a gyroscope as
presented in 'University physics' 9. ed. Young and Freedman - and containing the same
un-acknowledged flaw I point out to, about the occilations that reverses and cancels out the
accumulated torque (dL = torque*dt, dL modifying L as precession)).

snip


Carsten

Dear Carsten Troelsgaard:

"Carsten Troelsgaard" wrote in message
. ..

Precession of the Earth is, where I've seen it (see the .pdf link), being
presented as a torque
working on Earth periferal bulge eqvivalent to a gravitational pull in a
spinning gyroscope resting
it's end in a pivot.
Isn't that in error?

No, it is correct as far as the anaolgy goes. Precession does not include
"pole reversal", as you surmise below.

The principal axis is the Earth own spin-axis. If the Earth responds to
it's present inertia and
periferal bulge relative to the sun - without spinning itself - it would
have it's primary axis
plunging into
the plane of it's orbit around the Sun (tilt = 90 degrees).
....
What am I doing wrong?

You are applying a circumpolar torque, where none exists.

David A. Smith

Carsten Troelsgaard wrote:
Precession of the Earth is, where I've seen it (see the .pdf link), being presented as a torque
working on Earth periferal bulge eqvivalent to a gravitational pull in a spinning gyroscope resting
it's end in a pivot.

Obliquity-Induced Precession
http://scienceworld.wolfram.com/phys...recession.html

"Sam Wormley" skrev i en meddelelse news:bx5id.360429$D%.46858@attbi_s51...
Carsten Troelsgaard wrote:
Precession of the Earth is, where I've seen it (see the .pdf link), being presented as a torque
working on Earth periferal bulge eqvivalent to a gravitational pull in a spinning gyroscope
resting
it's end in a pivot.

Obliquity-Induced Precession
http://scienceworld.wolfram.com/phys...recession.html


The link starts:

"Because of the rotational flattening (obliquity) of a planet's figure ... "

I take that flattening and rotational flattening is two different things, - that is, if rotational
flattening = obliquety

Thanks for the link

Carsten

"N:dlzc D:aol T:com (dlzc)" N: dlzc1 D:cox skrev i en meddelelse
news:to5id.31484$SW3.25571@fed1read01...
Dear Carsten Troelsgaard:

"Carsten Troelsgaard" wrote in message
. ..

Precession of the Earth is, where I've seen it (see the .pdf link), being
presented as a torque
working on Earth periferal bulge eqvivalent to a gravitational pull in a
spinning gyroscope resting
it's end in a pivot.
Isn't that in error?

No, it is correct as far as the anaolgy goes. Precession does not include
"pole reversal", as you surmise below.

The principal axis is the Earth own spin-axis. If the Earth responds to
it's present inertia and
periferal bulge relative to the sun - without spinning itself - it would
have it's primary axis
plunging into
the plane of it's orbit around the Sun (tilt = 90 degrees).
...
What am I doing wrong?

You are applying a circumpolar torque, where none exists.

You are right. How blind can one be?
Thanks!

Carsten

"Carsten Troelsgaard" skrev i en meddelelse
. ..

"Sam Wormley" skrev i en meddelelse news:bx5id.360429$D%.46858@attbi_s51...
Carsten Troelsgaard wrote:
Precession of the Earth is, where I've seen it (see the .pdf link), being presented as a
torque
working on Earth periferal bulge eqvivalent to a gravitational pull in a spinning gyroscope
resting
it's end in a pivot.

Obliquity-Induced Precession
http://scienceworld.wolfram.com/phys...recession.html


The link starts:

"Because of the rotational flattening (obliquity) of a planet's figure ... "

I take that flattening and rotational flattening is two different things, - that is, if rotational
flattening = obliquety

That should be:

flattening = obliquety of a planet's figure

got it!

"Carsten Troelsgaard" skrev i en meddelelse news:4188f1ed$0$249

You are right. How blind can one be?
Thanks!

Anyway, as you may know, the initial question is something like this: Can some combination of
external forces impose a spiral structure on the surface of the Earth?

I tried to consider this:
If the vector of angular momentum is resolved into a vertical and a horizontal component (relative
to the eclipse), then I can consider the vertical in accordance to Earth primary axis, but the
horizontal (expressing the precession) may be 'at work' in the sense that it imposes a torque on
Earth.
Can this torque be released in the inner molten part of the Earth and leave a sheer-surface against
the crust ?

I could imagine that it would happen, but when I look at the instantaneous situation, an inner point
will be exposed to a resultant angular accelleration that changes direction every 12 hours - am I
having myself confused again?


Carsten