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In the angular momentum equation, L = r x p, when the magnitude of the radius changes, which one of the remaining variables is correctly conserved ?


Mandlbaur

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My point is actually that I should not be required to have to prove or disprove anything about any other theory prior to my work being considered.

 

My point is that you do need to show the required details not just hand wave them away. It is simple applications of force.

 

You should have absolutely no problem in showing how torque is involved. Or even showing how [latex] F_{21}=-F_{12}[/latex]

 

You posted one formula that doesn't even detail the conservation of angular momentum. It simply applies it.

 

Do you even know the proper conservation of angular momentum equation?

 

Your absolute refusal to even look at the mathematical proofs tells otherwise and proves to me that you do not know the details. If you did you would have had no problem posting such. There is classical proofs that don't require latex to be legible.

 

Simply looking at L=R×P isn't the full story.

 

when [latex] \vec{L}[/latex] is constant when net [latex]\tau=0[/latex] (torque) is your specific conservation of angular momentum relation. That is what you have to prove as false.

 

Or more accurately start with [latex]\vec{\tau}=\frac{d\vec{L}}{dt}[/latex] where net torque equals zero and [latex] \Delta L=constant[/latex]

Edited by Mordred
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Any system to which the formula I have specified in my paper can be realistically applied is proven by my paper to not conserve angular momentum when the radius changes.

 

 

 

 

But this is not what you originally said.

 

 

 

 

Mandlbaur post#1

 

Both angular momentum and momentum are accepted to be conserved values and both of these are contained within the equation L = r x p. Assuming the implied rotation around a central point, they cannot both be conserved when the magnitude of the radius changes. The generally accepted principle is that momentum must change in order to conserve angular momentum. However it is logically proven that it is the component of momentum perpendicular to the radius which must be conserved.

 

 

 

Originally you said the above applies to any rotation (around a central point but what other sort of rotation is there?)

Later you changed this to a fixed central point, without defining fixed.

 

 

So I have a list of excluded examples of systems to which your statements can be applied , but no included ones.

 

 

You have not provided a single example of a single system to which your analysis applies, despite several requests for one.

 

 

So I have explored a number of examples of genuinely rotating systems with you, and you have rejected all of them as not analysable by your method.

 

 

You are adamant that it is applicable to a system with a centre that is fixed or not going anywhere, yet you are equally adamant that this system with zero translational velocity has a momentum (note not angular momentum)

 

 

How is this possible?

 

 

You claim that the generally accepted principle is that momentum should change if the radius changes.

 

But the system, by definition, has no momentum to change.

 

It only possesses angular momentum.

 

 

 

I have no idea what books you have been reading about mechanics, but your opening statement suggests to me that you have only partly understood them.

 

In particular it is true that the most common cited example of the effect you describe incorrectly is that of the skater spinning on the spot.

 

 

The skater's angular velocity increases as she draws her arms inwards.

She has no momentum because she is spinning on the spot, but she has angular momentum, which remains constant (is conserved) so as the radius decreases the angular velocity increases, just as you say.

But her momentum does not increase, which is not as you say.

This is all possible because of the very low friction on ice so we assume no driving forces are required.

 

 

 

In the case of carousel or weight on the end of a rope, a driving force is required.

 

 

 

And this must be included in the system for analysis, which you are not doing, but everyone here is telling you that you need to do.

 

 

 

We have been trying to help you create a correct analysis of rotating systems that can be applied as widely as possible, not one that has to exclude every example that is presented.

 

 

Since you have obviously already put in a great deal of effort into this, I can only urge you to study some basic mechanics texts.

I suggest engineering science ones would be better as they are more self contained and plain speaking than applied maths or physics ones which also rely heavily on a whole raft of peripheral background material.

 

This would help you understand when momentum and /or angular momentum is destroyed and when they are conserved and how to include all the necessary items in a system.

Edited by studiot
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This would help you understand when momentum and /or angular momentum is destroyed and when they are conserved and how to include all the necessary items in a system.

I agree with this need completely also with using the engineering references to start with. This is one of those cases where its more readily understood compared to Noethers theorem/action

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Well, in point of fact you do - you have to get others to choose to take you seriously in order to get your work considered. I think today hasn't been a very good day for you in that respect.

 

One last time: angular momentum is conserved in all closed systems. If you have accurately measured some apparatus exhibiting a changing angular momentum, then it is not a closed system. End of story, and I am done here.

 

 

 

My point is that you do need to show the required details not just hand wave them away. It is simple applications of force.

 

You should have absolutely no problem in showing how torque is involved. Or even showing how [latex] F_{21}=-F_{12}[/latex]

 

You posted one formula that doesn't even detail the conservation of angular momentum. It simply applies it.

 

Do you even know the proper conservation of angular momentum equation?

 

Your absolute refusal to even look at the mathematical proofs tells otherwise and proves to me that you do not know the details. If you did you would have had no problem posting such. There is classical proofs that don't require latex to be legible.

 

Simply looking at L=R×P isn't the full story.

 

when [latex] \vec{L}[/latex] is constant when net [latex]\tau=0[/latex] (torque) is your specific conservation of angular momentum relation. That is what you have to prove as false.

 

Or more accurately start with [latex]\vec{\tau}=\frac{d\vec{L}}{dt}[/latex] where net torque equals zero and [latex] \Delta L=constant[/latex]

 

 

 

 

But this is not what you originally said.

 

 

 

 

 

 

Originally you said the above applies to any rotation (around a central point but what other sort of rotation is there?)

Later you changed this to a fixed central point, without defining fixed.

 

 

So I have a list of excluded examples of systems to which your statements can be applied , but no included ones.

 

 

You have not provided a single example of a single system to which your analysis applies, despite several requests for one.

 

 

So I have explored a number of examples of genuinely rotating systems with you, and you have rejected all of them as not analysable by your method.

 

 

You are adamant that it is applicable to a system with a centre that is fixed or not going anywhere, yet you are equally adamant that this system with zero translational velocity has a momentum (note not angular momentum)

 

 

How is this possible?

 

 

You claim that the generally accepted principle is that momentum should change if the radius changes.

 

But the system, by definition, has no momentum to change.

 

It only possesses angular momentum.

 

 

 

I have no idea what books you have been reading about mechanics, but your opening statement suggests to me that you have only partly understood them.

 

In particular it is true that the most common cited example of the effect you describe incorrectly is that of the skater spinning on the spot.

 

 

The skater's angular velocity increases as she draws her arms inwards.

She has no momentum because she is spinning on the spot, but she has angular momentum, which remains constant (is conserved) so as the radius decreases the angular velocity increases, just as you say.

But her momentum does not increase, which is not as you say.

This is all possible because of the very low friction on ice so we assume no driving forces are required.

 

 

 

In the case of carousel or weight on the end of a rope, a driving force is required.

 

 

 

And this must be included in the system for analysis, which you are not doing, but everyone here is telling you that you need to do.

 

 

 

We have been trying to help you create a correct analysis of rotating systems that can be applied as widely as possible, not one that has to exclude every example that is presented.

 

 

Since you have obviously already put in a great deal of effort into this, I can only urge you to study some basic mechanics texts.

I suggest engineering science ones would be better as they are more self contained and plain speaking than applied maths or physics ones which also rely heavily on a whole raft of peripheral background material.

 

This would help you understand when momentum and /or angular momentum is destroyed and when they are conserved and how to include all the necessary items in a system.

 

Every argument you guys have presented, I have defeated. In my view this is the point at which you should begin to take me seriously. However you have have claimed more than once to have defeated me on multiple occasions. This can only be the result of a confirmation bias.

 

Since you are exhibiting confirmation bias behaviour, it is impossible for me to get you to choose to take my work seriously. In fact you will choose the opposite in order to support your position despite the facts of the matter.

 

You are making unsupported claims and backing them up with invalid argument and then denying to yourself that your arguments have been shown invalid. This is the classical biased behaviour that I have faced continually over the past year.

 

The fact is that you have never even tried to create an apparatus to test this world view of yours yet you will adamantly claim that my various apparatus were somehow flawed.

 

How do you suggest I tackle this?

 

I am prepared to put up a scientific wager that an apparatus which you design (I'll even cover the costs of it) will prove my work to be correct.

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You have defeated absolutely nothing. All you've done is shown that you do not understand the conditions that apply to conservation of angular momentum.

If you could address our questions with proper knowledge on the topic you would have.

 

 

 

Both angular momentum and momentum are accepted to be conserved values and both of these are contained within the equation L = r x p. Assuming the implied rotation around a central point, they cannot both be conserved when the magnitude of the radius changes. The generally accepted principle is that momentum must change in order to conserve angular momentum.

 

This very line is full of mistakes already mentioned numerous times.



 

But the system, by definition, has no momentum to change.

It only possesses angular momentum.

The skater's angular velocity increases as she draws her arms inwards.

She has no momentum because she is spinning on the spot, but she has angular momentum, which remains constant (is conserved) so as the radius decreases the angular velocity increases, just as you say.

But her momentum does not increase, which is not as you say.

This is all possible because of the very low friction on ice so we assume no driving forces are required.


 

 

 

please note the mistakes via what Studiot posted. "the system only possesses angular momentum, not linear momentum"

 

Please state the conservation law of angular momentum correctly as :When the net external torque acting upon a system about a given axis is zero the total angular momentum about that axis remains constant."

 

That is the correct definition.

 

[latex] if \sum \vec{\tau}=0,, then \vec{L}=constant[/latex]

 

any other definition not equivalent is false to what is conserved in angular momentum. The law states nothing about conservation of linear momentum. That is a different law with a different mathematical proof. As Studiot pointed out there is no linear momentum in the system by definition.

Edited by Mordred
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You have defeated absolutely nothing. All you've done is shown that you do not understand the conditions that apply to conservation of angular momentum.

 

If you could address our questions with proper knowledge on the topic you would have.

 

 

 

 

This very line is full of mistakes already mentioned numerous times.

 

 

Please point out any mistake in that line?

 

The reality is that there are actually none.

 

I admitted a mistake (The "fixed") because it was easier to do that (and slightly restrict the application of my paper) to defeat yet another invalid argument levelled against my work than to try to explain that the example provided in the detractors argument actually uses a different equation and then go down a whole other avenue.

 

Just saying I should have used "fixed" solved the problem even if it slightly restricted the application of my paper.

 

In reality the "fixed" is not necessary and it is not actually a mistake. My paper is perfectly valid whether the "fixed" is there or not.

 

But you have claimed that my abstract is "full of mistakes" mentioned "numerous times".

 

Frankly this claim is complete nonsense. You will not be able to back it up. You should be moderated out of this discussion for making invalid claims which you are not prepared to support.

Edited by Mandlbaur
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really you refer to both momentum and angular being both conserved when there is no linear momentum to conserve in the first place within your system ? And you claim this is correct?

Linear momentum is a vector whose direction is parallel to the velocity of the particle. with relations p=mv So pray tell where is your momentum term?

in angular momentum the vector is a cross product which is a binary operation of 2 vectors in R^3 two completely different vectors. There is no right hand rule in the former for example.

"The definition of angular momentum for a point particle is a pseudovector r×p, the cross product of the particle's position vector r (relative to some origin)"
https://en.wikipedia.org/wiki/Angular_momentum

you can read it for yourself. Key note torque is used..... but also note the mention of torque on the cross product link in particular with regards to moment of force.

So have I been steering you falsely or asking you to recognize these details which are 100% applicable.

Here is a mathematical proof showing the equation and definition I posted above.

http://www.citycollegiate.com/centre_of_mass3.htm

 

I was digging for a decent proof without applying Noether's this one will suit

Edited by Mordred
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Every argument you guys have presented, I have defeated. In my view this is the point at which you should begin to take me seriously.

 

The falseness of the first sentence is the reason the second is not happening.

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This "proof" is flawed.

 

A vector cross product is not commutative.

 

You're right: a x b = - b x a. So they need a negative sign in one spot. But then they proceed to show that the affected term is zero. So the proof still works even if you correct the sign error.

 

Out of all the "combative" threads I've run across on this forum, this one takes the cake. And you refused to answer me when I asked you why you want conservation of angular momentum to be wrong so badly - I suspect you're trying to cook up a free energy device of some kind. I'm really sorry that the universe doesn't work the way you want it to; if I could edit the laws of physics there'd be some changes I'd make too. Oh well...

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Mandlbaur post#54

 

Every argument you guys have presented, I have defeated.

 

 

Mandlbaur post#56

 

I admitted a mistake (The "fixed") because it was easier to do that (and slightly restrict the application of my paper) to defeat yet another invalid argument levelled against my work than to try to explain that the example provided in the detractors argument actually uses a different equation and then go down a whole other avenue.

 

 

One of these two statements can't be correct.

 

 

 

Like KipIngram I am still waiting for a reasonable response to my offered helpful discussion.

I sincerely hope the above extract does not mean you are saying you actually made no mistake, just admitted one for convenience.

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You're right: a x b = - b x a. So they need a negative sign in one spot. But then they proceed to show that the affected term is zero. So the proof still works even if you correct the sign error.

 

Out of all the "combative" threads I've run across on this forum, this one takes the cake. And you refused to answer me when I asked you why you want conservation of angular momentum to be wrong so badly - I suspect you're trying to cook up a free energy device of some kind. I'm really sorry that the universe doesn't work the way you want it to; if I could edit the laws of physics there'd be some changes I'd make too. Oh well...

 

 

Flawed is flawed. You would not grant me any leeway if there were such an infantile error in my work.

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There is a subtle difference between angular momentum and moment of momentum.

 

Do you know what it is?

 

Hint it corresponds to the differnce between a couple and the moment of a force.

 

Are you asking me or Mandibaur?

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Are you asking me or Mandibaur?

 

Why would I ask you?

 

I'm sorry if my intent was unclear.

 

I do think that not understanding this difference may underlie Mandlbaur's difficulties.

 

You are welcome to explain if you like, particularly as he won't talk to me for some reason.

Edited by studiot
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I didn't think you meant me, but rather than ignore it I thought I'd just be sure. :) And no, I think we've thoroughly provided right guidance here - he's just not interested in listening. It was really surprising to see someone come right out the gates with such a chip on his shoulder.


It's also weird to see someone put up such a fight about something so simple and elementary - usually discussions like this revolve around something at least moderately complicated and opaque. It doesn't get much more basic than a direct conservation law.

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Especially considering how many textbooks etc contain proofs in numerous metric forms. The topic is incredibly well researched. Yet the OP feels his 1 page proof is sufficient to overcome a huge body of research.

 

To the point of merely hinting greater rigor will be needed and getting rather defensive.

Edited by Mordred
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Especially considering how many textbooks etc contain proofs in numerous metric forms. The topic is incredibly well resrarched.

 

Yes. This feels much more like someone who enjoys arguing and is trying to pick a fight than someone who's pursuing knowledge.

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The proof I provided on that link is one of the simpler proofs to understand. I'm positive Studiot has far more detailed. Without requiring a huge body of knowledge on other metric systems

 

Yes. This feels much more like someone who enjoys arguing and is trying to pick a fight than someone who's pursuing knowledge.

You often see that on any forum lol

Edited by Mordred
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Aside from all your incredible patience, I liked this part:

 

I have a knowledge of the topic because of my work which included the design, manufacture and testing of many experimental prototypes. Each one an optimised version of the previous model. All of them attempts to achieve extremely high magnitudes of angular velocity predicted by conservation of angular momentum. All of them indicating that angular momentum is not conserved in variable radii systems.

 

I have spent much time trying to understand why and have discovered the truth and pinpointed the problem. I have written three different proofs of this. This paper being the latest iteration of my second proof.

 

Clearly this is extremely difficult for people to accept. I understand that it is akin to physical pain for a person to have to change their world view. I'm sorry about that.

 

Unfortunately because I am the one who has stumbled on this, I am tasked with getting it known and therefore have no option but to continue to push this heavy stone up this endless hill until somebody listens.

 

OP - "I have defeated all of you!" hahaha honestly I'm surprised there is wifi in the looney hospitals

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What you are doing is called ad-hominem.

 

Allow me to bring your attention back to the fact that my paper as presented is a logical proof.

 

In order to dismiss the conclusion drawn one would have to invalidate my premises or fault my logic.

 

Providing alternative theories does not do it. Accusing me of having a lack of understanding and calling me names doesn't do it.

 

Accusing me of being the aggressor in this discussion is simply incorrect. I am defending my position from your aggression. It is yourselves who are being combative.

 

This is a result of your cognitive dissonance due to your inability to accept or defeat my work.

 

It is unfortunate, but it is also true.

 

If there was any way for me to present this without triggering confirmation bias, believe me, I would try that.

 

The reality is that you are all making fools of yourselves and I am sorry that it has to be this way.

 

Veritas omnia vincit

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!

Moderator Note

Can we clarify any further questions and make our points without all the sniping? Scientific discussion requires rigor on both sides, but can do without personal judgements and harmful language. Let's learn something here.

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In order to dismiss the conclusion drawn one would have to invalidate my premises or fault my logic.

 

 

Actually, no.

 

If you can be shown to be wrong (which you obviously are) then it is not necessary to analyse the nature of your error. Although it would be a valuable learning experience for you to do that.

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You asked that I backed up that torsion is applicable to your article gaining weight. I provided a simpler mathematical proof to support my assessment.

I also quoted a passage that I stated was in error as there is two main classifications of momentum. Linear and angular. They both have distinctive formulas and definitions from each other. Your system has no linear momentum. However that's been mentioned already

 

My question is on the distinctions

Don't you think its important to note

 

those distinctions in your article ? The formulas for angular momentum uses torque.

 

They don't use linear momentum. Yet your article compares linear momentum to angular momentum. The linear momentum is zero.

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