• #### Re: What we know about the gyroscope

From Paul B. Andersen@21:1/5 to All on Mon Dec 4 11:08:24 2023
Den 04.12.2023 06:08, skrev patdolan:
1. All angular momentum has a "rigidity in space", even the so-called minor axis theorem, aka tennis racket theorem.

2. When angular momentum is torqued it is immediately met by an opposing torque of exactly the same magnitude and in exactly the opposite direction.

3. In the event of #2 another, much smaller angular momentum instantly appears which is always perpendicular to the original angular momentum. This is commonly referred to as precession.

4. None of the aforementioned enigmatic behaviors are understood in anyway by any physics, past or present. And they cannot be derived from first principles of any physics, past or present.

Quite.
Physics can't be derived from 'first principles'.
Physics is derived from observations of HOW Nature behaves.

Nobody knows WHY Nature behaves in the enigmatic way she does.
You can't understand WHY Newton's laws of motion are as they are.

But we know that the mathematical model of an aspect of Nature:
Newtonian mechanics, correctly predicts HOW a gyroscope will behave.

Physics doesn't answer or explain WHY, it only predicts HOW.

--
Paul

https://paulba.no/

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• From Tom Roberts@21:1/5 to patdolan on Mon Dec 4 10:05:43 2023
On 12/3/23 11:08 PM, patdolan wrote:
1. All angular momentum has a "rigidity in space", even the
so-called minor axis theorem, aka tennis racket theorem.

Hmmmm. This is poorly stated at best.

For an isolated system in which the Lagrangian is rotationally
invariant, angular momentum is conserved. Note this does not apply to a gyroscope near the surface of the earth and supported against gravity.

2. When angular momentum is torqued it is immediately met by an
opposing torque of exactly the same magnitude and in exactly the
opposite direction.

This is just plain wrong. Invoking MAGIC is useless.

3. In the event of #2 another, much smaller angular momentum
instantly appears which is always perpendicular to the original
angular momentum. This is commonly referred to as precession.

This is also just plain wrong. Invoking MAGIC is useless.

4. None of the aforementioned enigmatic behaviors are understood in
anyway by any physics, past or present. And they cannot be derived
from first principles of any physics, past or present.

This just happens to be right, BECAUSE THEY ARE WRONG.

The precession of a gyroscope is easily derived using Newton's laws
applied to the gyroscope. It is probably easier to use Lagrangian mechanics.

PS--the Big Ben Paradox has again succeeded is raising a lot of hell

How silly, as "the big ben paradox" is merely patdolan's lack of
understanding of very basic physics.

Tom Roberts

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• From Volney@21:1/5 to patdolan on Mon Dec 4 15:21:09 2023
On 12/4/2023 12:08 AM, patdolan wrote:

4. None of the aforementioned enigmatic behaviors are understood in anyway by any physics, past or present. And they cannot be derived from first principles of any physics, past or present.

No, showing the existence of the torque/precession is a second semester freshman physics problem. Best way to treat it is to consider the
rotating mass as many smaller masses instantaneously moving in a
straight line but rigidly attached to the hub and showing how the system
reacts to an instantaneous force. Newton figured this out long ago.

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• From Sylvia Else@21:1/5 to patdolan on Tue Dec 5 13:15:35 2023
On 05-Dec-23 12:54 pm, patdolan wrote:
On Monday, December 4, 2023 at 12:21:12 PM UTC-8, Volney wrote:
On 12/4/2023 12:08 AM, patdolan wrote:

4. None of the aforementioned enigmatic behaviors are understood in anyway by any physics, past or present. And they cannot be derived from first principles of any physics, past or present.
No, showing the existence of the torque/precession is a second semester
freshman physics problem. Best way to treat it is to consider the
rotating mass as many smaller masses instantaneously moving in a
straight line but rigidly attached to the hub and showing how the system
reacts to an instantaneous force. Newton figured this out long ago.

The two most important, most ignored and most unexplained properties of the gyroscope are 1) rigidity, and 2) the instantaneous and perfectly opposing torque which magically appears and exactly balances the applied torque to prevent the g-scope from
tipping over while it precesses.

You've just been told how to analyse a gyroscope, but you ignore that
and go back to magic.

Sylvia.

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• From Volney@21:1/5 to patdolan on Mon Dec 4 22:14:16 2023
On 12/4/2023 8:54 PM, patdolan wrote:
On Monday, December 4, 2023 at 12:21:12 PM UTC-8, Volney wrote:
On 12/4/2023 12:08 AM, patdolan wrote:

4. None of the aforementioned enigmatic behaviors are understood in anyway by any physics, past or present. And they cannot be derived from first principles of any physics, past or present.

No, showing the existence of the torque/precession is a second semester
freshman physics problem. Best way to treat it is to consider the
rotating mass as many smaller masses instantaneously moving in a
straight line but rigidly attached to the hub and showing how the system
reacts to an instantaneous force. Newton figured this out long ago.

The two most important, most ignored and most unexplained properties of the gyroscope are 1) rigidity, and 2) the instantaneous and perfectly opposing torque which magically appears and exactly balances the applied torque to prevent the g-scope from
tipping over while it precesses.

You flunk freshman physics, Semester 2. The properties of gyroscopes is
not "unexplained properties" but are well understood physics as I
stated. Just because you aren't smart enough to understand it doesn't
mean it's wrong or nobody understands it, it just means you're just not
smart enough.

Nor is the gyroscope not tipping over any form of "magic", conservation
of angular momentum is enough to explain "why" a gyroscope doesn't fall
over.

(a common trait of cranks is that they seem to think that if they don't understand something either it's wrong or they project their lack of understanding onto /everyone/, implying /nobody/ understands it)

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• From Mikko@21:1/5 to patdolan on Tue Dec 5 12:45:31 2023
On 05-Dec-23 12:54 pm, patdolan wrote:

The two most important, most ignored and most unexplained properties
of the gyroscope are 1) rigidity,

The approximate rigidity is a consequence of the properties of the
material the gyroscope is made of.

and 2) the instantaneous and perfectly opposing torque which magically appears and exactly balances the applied torque to prevent the g-scope
from tipping over while it precesses.

When you look at the gyroscope you don't see torque, you just see motion.
For the explanation of the motion, see e.g. Goldstein: Classical Mchanics sections 5-6 and 5-7.

Mikko

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• From Mikko@21:1/5 to patdolan on Wed Dec 6 11:28:04 2023
On 2023-12-05 19:07:38 +0000, patdolan said:

On Tuesday, December 5, 2023 at 2:45:36 AM UTC-8, Mikko wrote:
On 05-Dec-23 12:54 pm, patdolan wrote:
The two most important, most ignored and most unexplained properties
of the gyroscope are 1) rigidity,
The approximate rigidity is a consequence of the properties of the
material the gyroscope is made of.
and 2) the instantaneous and perfectly opposing torque which magically
appears and exactly balances the applied torque to prevent the g-scope >>> > from tipping over while it precesses.
When you look at the gyroscope you don't see torque, you just see motion.
For the explanation of the motion, see e.g. Goldstein: Classical Mchanics
sections 5-6 and 5-7.

Look at me, Mikko,

I don't see anything.

and listen very carefully. ALL treatments of gyroscopes, including the
one you reference, start in the middle of the story by starting with precession.

No, Goldstein starts the section 5-7 with equations of kinetic and
potential energy and infers from them that the motion involves
precession and nutation.

Mikko

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• From Mikko@21:1/5 to patdolan on Thu Dec 7 12:17:34 2023
On 2023-12-07 00:55:20 +0000, patdolan said:

On Wednesday, December 6, 2023 at 1:28:09 AM UTC-8, Mikko wrote:
On 2023-12-05 19:07:38 +0000, patdolan said:
On Tuesday, December 5, 2023 at 2:45:36 AM UTC-8, Mikko wrote:
On 05-Dec-23 12:54 pm, patdolan wrote:
The two most important, most ignored and most unexplained
properties of the gyroscope are 1) rigidity,
The approximate rigidity is a consequence of the properties of the
material the gyroscope is made of.
and 2) the instantaneous and perfectly opposing torque which
magically appears and exactly balances the applied torque to
prevent the g-scope from tipping over while it precesses.
When you look at the gyroscope you don't see torque, you just see
motion. For the explanation of the motion, see e.g. Goldstein:
Classical Mchanics sections 5-6 and 5-7.
Look at me, Mikko,
I don't see anything.
and listen very carefully. ALL treatments of gyroscopes, including the
one you reference, start in the middle of the story by starting with
precession.
No, Goldstein starts the section 5-7 with equations of kinetic and>
potential energy and infers from them that the motion involves>
precession and nutation.
Mikko, I have carefully studied Goldstein 5-7 https://www.math.toronto.edu/khesin/biblio/GoldsteinPooleSafkoClassicalMechanics.pdf

and can identify neither an equation(s) or a sentence which "infers" precession and nutation from potential angular energy, kinetic &
potential. Please direct me to the precise eqn(s) or the paragraph.

The equation for procession is (5-50). The equation for nutation is (5-53)
and in another way (5-55). Another equation for precession is (5-66).
The equation for average precession is (5-67).

When a spin axis is first held fixed and then released, keeping ony one
point fixed, the spin axis first starts to fall. This conclusion is
stated in the text before the paragraph that contains the equation (5-58).

The inferences to each of these equations is evertything from the third paragraph to the equation. There is very little other comments in the
text.

Mikko

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