| Topic: |
Science > Physics |
| User: |
"PD" |
| Date: |
31 May 2007 11:59:12 AM |
| Object: |
Re: Conservation of angular momentum |
On May 31, 11:52 am, Peter <Poakfi...@msn.com> wrote:
On May 31, 12:00 pm, PD <TheDraperFam...@gmail.com> wrote:
On May 31, 10:48 am, Peter <Poakfi...@msn.com> wrote:
On May 31, 11:20 am, PD <TheDraperFam...@gmail.com> wrote:
On May 31, 9:06 am, Peter <Poakfi...@msn.com> wrote:
On May 30, 10:44 pm, PD <TheDraperFam...@gmail.com> wrote:
On May 30, 5:19 pm, "Androcles" <Engin...@hogwarts.physics> wrote:
"Peter" <Poakfi...@msn.com> wrote in message
[snip old stuff we agree with]
OK. Snipped.
Oh, so sorry, that's YOUR line.
PD
I wrote an article about it, and submitted it to a physics journal,
but it was promptly rejected, without giving me any reason.
Peter
Did you not ask for the reviewer's comments? Did you not submit it to
another journal?
You do know, don't you, that Einstein, Bohr, and others had to submit
their work to several places, being rejected several times first?
You do know, don't you, that modifying a paper in response to referee
remarks is what *all* physicists do when they publish?
PD
PD- Hide quoted text -
- Show quoted text -
Gee, thank you for your comforting words. I did not know all of that.
One of the editors of the journal told me that he would not send my
manuscript to a referee, because he had taught classical mechanics,
Then there is your reviewer from whom you should have solicited
remarks.
implying the he knew all about the subject, that everything was
already known, and that there was nothing else I could add. I have not
submitted it to other journals, because I gather there is only one
that is significant.
This last clause is CERTAINLY not true. If you walk into any
university science library and ask for the physics journals, you will
be greeted with stacks and stacks of them. It might do you well to
acquaint yourself with them a little better.
Besides the journals published by APS, could you please mention some
that are worthwhile, I mean in the US?
Peter
http://www.ifpan.edu.pl/journal.html
There are dozens of APS journals.
You've also neglected AIP journals completely.
There is also no reason why you shouldn't submit to Zeitschrift fur
Physik or the European Physical Journal, for example, since each
distributes to the US and is in English.
PD
.
|
|
| User: "Peter" |
|
| Title: Re: Conservation of angular momentum |
31 May 2007 04:56:43 PM |
|
|
On May 31, 12:59 pm, PD <TheDraperFam...@gmail.com> wrote:
On May 31, 11:52 am, Peter <Poakfi...@msn.com> wrote:
On May 31, 12:00 pm, PD <TheDraperFam...@gmail.com> wrote:
On May 31, 10:48 am, Peter <Poakfi...@msn.com> wrote:
On May 31, 11:20 am, PD <TheDraperFam...@gmail.com> wrote:
On May 31, 9:06 am, Peter <Poakfi...@msn.com> wrote:
On May 30, 10:44 pm, PD <TheDraperFam...@gmail.com> wrote:
On May 30, 5:19 pm, "Androcles" <Engin...@hogwarts.physics> wrote:
"Peter" <Poakfi...@msn.com> wrote in message
[snip old stuff we agree with]
OK. Snipped.
Oh, so sorry, that's YOUR line.
PD
I wrote an article about it, and submitted it to a physics journal,
but it was promptly rejected, without giving me any reason.
Peter
Did you not ask for the reviewer's comments? Did you not submit it to
another journal?
You do know, don't you, that Einstein, Bohr, and others had to submit
their work to several places, being rejected several times first?
You do know, don't you, that modifying a paper in response to referee
remarks is what *all* physicists do when they publish?
PD
PD- Hide quoted text -
- Show quoted text -
Gee, thank you for your comforting words. I did not know all of that.
One of the editors of the journal told me that he would not send my
manuscript to a referee, because he had taught classical mechanics,
Then there is your reviewer from whom you should have solicited
remarks.
implying the he knew all about the subject, that everything was
already known, and that there was nothing else I could add. I have not
submitted it to other journals, because I gather there is only one
that is significant.
This last clause is CERTAINLY not true. If you walk into any
university science library and ask for the physics journals, you will
be greeted with stacks and stacks of them. It might do you well to
acquaint yourself with them a little better.
Besides the journals published by APS, could you please mention some
that are worthwhile, I mean in the US?
Peter
http://www.ifpan.edu.pl/journal.html
There are dozens of APS journals.
You've also neglected AIP journals completely.
There is also no reason why you shouldn't submit to Zeitschrift fur
Physik or the European Physical Journal, for example, since each
distributes to the US and is in English.
Physical Review told me that once a manuscript is rejected by one
journal, it cannot be submitted to any other. AIP told me it does not
publish articles with original research. I would prefer to stick to
American journals, if possible. I think if I made a better exposition
of my case, they would not reject it, but I need someone to give me a
hand to do it. Also, they ask one to suggest qualified referees to
review the paper. I need someone to read my article, understand it,
correct it if necessary, and agree it should be published. I have not
been able to find someone willing to at least read it. I suspect the
guy at PR did not read my manuscript.
Peter
.
|
|
|
| User: "PD" |
|
| Title: Re: Conservation of angular momentum |
31 May 2007 05:42:48 PM |
|
|
On May 31, 4:56 pm, Peter <Poakfi...@msn.com> wrote:
On May 31, 12:59 pm, PD <TheDraperFam...@gmail.com> wrote:
On May 31, 11:52 am, Peter <Poakfi...@msn.com> wrote:
On May 31, 12:00 pm, PD <TheDraperFam...@gmail.com> wrote:
On May 31, 10:48 am, Peter <Poakfi...@msn.com> wrote:
On May 31, 11:20 am, PD <TheDraperFam...@gmail.com> wrote:
On May 31, 9:06 am, Peter <Poakfi...@msn.com> wrote:
On May 30, 10:44 pm, PD <TheDraperFam...@gmail.com> wrote:
On May 30, 5:19 pm, "Androcles" <Engin...@hogwarts.physics> wrote:
"Peter" <Poakfi...@msn.com> wrote in message
[snip old stuff we agree with]
OK. Snipped.
Oh, so sorry, that's YOUR line.
PD
I wrote an article about it, and submitted it to a physics journal,
but it was promptly rejected, without giving me any reason.
Peter
Did you not ask for the reviewer's comments? Did you not submit it to
another journal?
You do know, don't you, that Einstein, Bohr, and others had to submit
their work to several places, being rejected several times first?
You do know, don't you, that modifying a paper in response to referee
remarks is what *all* physicists do when they publish?
PD
PD- Hide quoted text -
- Show quoted text -
Gee, thank you for your comforting words. I did not know all of that.
One of the editors of the journal told me that he would not send my
manuscript to a referee, because he had taught classical mechanics,
Then there is your reviewer from whom you should have solicited
remarks.
implying the he knew all about the subject, that everything was
already known, and that there was nothing else I could add. I have not
submitted it to other journals, because I gather there is only one
that is significant.
This last clause is CERTAINLY not true. If you walk into any
university science library and ask for the physics journals, you will
be greeted with stacks and stacks of them. It might do you well to
acquaint yourself with them a little better.
Besides the journals published by APS, could you please mention some
that are worthwhile, I mean in the US?
Peter
http://www.ifpan.edu.pl/journal.html
There are dozens of APS journals.
You've also neglected AIP journals completely.
There is also no reason why you shouldn't submit to Zeitschrift fur
Physik or the European Physical Journal, for example, since each
distributes to the US and is in English.
Physical Review told me that once a manuscript is rejected by one
journal, it cannot be submitted to any other.
That is not true.
AIP told me it does not
publish articles with original research.
That is also not true, though since all published work needs to be
original, I don't know what your definition of "original" is.
I would prefer to stick to
American journals, if possible. I think if I made a better exposition
of my case, they would not reject it, but I need someone to give me a
hand to do it. Also, they ask one to suggest qualified referees to
review the paper. I need someone to read my article, understand it,
correct it if necessary, and agree it should be published. I have not
been able to find someone willing to at least read it. I suspect the
guy at PR did not read my manuscript.
Peter
Have you considered hiring someone to review your paper? That's what
book authors do.
PD
.
|
|
|
| User: "Peter" |
|
| Title: Re: Conservation of angular momentum |
01 Jun 2007 09:26:52 AM |
|
|
On May 31, 6:42 pm, PD <TheDraperFam...@gmail.com> wrote:
On May 31, 4:56 pm, Peter <Poakfi...@msn.com> wrote:
On May 31, 12:59 pm, PD <TheDraperFam...@gmail.com> wrote:
On May 31, 11:52 am, Peter <Poakfi...@msn.com> wrote:
On May 31, 12:00 pm, PD <TheDraperFam...@gmail.com> wrote:
On May 31, 10:48 am, Peter <Poakfi...@msn.com> wrote:
On May 31, 11:20 am, PD <TheDraperFam...@gmail.com> wrote:
On May 31, 9:06 am, Peter <Poakfi...@msn.com> wrote:
On May 30, 10:44 pm, PD <TheDraperFam...@gmail.com> wrote:
On May 30, 5:19 pm, "Androcles" <Engin...@hogwarts.physics> wrote:
"Peter" <Poakfi...@msn.com> wrote in message
[snip old stuff we agree with]
OK. Snipped.
Oh, so sorry, that's YOUR line.
PD
I wrote an article about it, and submitted it to a physics journal,
but it was promptly rejected, without giving me any reason.
Peter
Did you not ask for the reviewer's comments? Did you not submit it to
another journal?
You do know, don't you, that Einstein, Bohr, and others had to submit
their work to several places, being rejected several times first?
You do know, don't you, that modifying a paper in response to referee
remarks is what *all* physicists do when they publish?
PD
PD- Hide quoted text -
- Show quoted text -
Gee, thank you for your comforting words. I did not know all of that.
One of the editors of the journal told me that he would not send my
manuscript to a referee, because he had taught classical mechanics,
Then there is your reviewer from whom you should have solicited
remarks.
implying the he knew all about the subject, that everything was
already known, and that there was nothing else I could add. I have not
submitted it to other journals, because I gather there is only one
that is significant.
This last clause is CERTAINLY not true. If you walk into any
university science library and ask for the physics journals, you will
be greeted with stacks and stacks of them. It might do you well to
acquaint yourself with them a little better.
Besides the journals published by APS, could you please mention some
that are worthwhile, I mean in the US?
Peter
http://www.ifpan.edu.pl/journal.html
There are dozens of APS journals.
You've also neglected AIP journals completely.
There is also no reason why you shouldn't submit to Zeitschrift fur
Physik or the European Physical Journal, for example, since each
distributes to the US and is in English.
Physical Review told me that once a manuscript is rejected by one
journal, it cannot be submitted to any other.
That is not true.
It is, I can assure you.
AIP told me it does not
publish articles with original research.
That is also not true, though since all published work needs to be
original, I don't know what your definition of "original" is.
It is true, the American Journal of Physics told me I should submit my
work to a "research journal."
I would prefer to stick to
American journals, if possible. I think if I made a better exposition
of my case, they would not reject it, but I need someone to give me a
hand to do it. Also, they ask one to suggest qualified referees to
review the paper. I need someone to read my article, understand it,
correct it if necessary, and agree it should be published. I have not
been able to find someone willing to at least read it. I suspect the
guy at PR did not read my manuscript.
Peter
Have you considered hiring someone to review your paper? That's what
book authors do.
I don't have that kind of money.
Peter
.
|
|
|
| User: "Timo A. Nieminen" |
|
| Title: Re: Conservation of angular momentum |
01 Jun 2007 03:25:23 PM |
|
|
On Fri, 1 Jun 2007, Peter wrote:
On May 31, 6:42 pm, PD <TheDraperFam...@gmail.com> wrote:
On May 31, 4:56 pm, Peter <Poakfi...@msn.com> wrote:
Physical Review told me that once a manuscript is rejected by one
journal, it cannot be submitted to any other.
That is not true.
It is, I can assure you.
No. Some publishers have policies that if a paper is rejected by one of
_their_ journals, it can't be submitted to another of _their_ journals. So
try another publisher. APS publishes, what, about 8 journals? A small,
small (but influential) fraction of the physics journals worldwide.
It isn't even true that an article rejected by one APS journal can't be
submitted to another APS journal. Rejection by PRL is often followed by
submission to PR(A-E). The APS website is even set up to make it easy to
do so. If rejected by PR(A-E), then you shouldn't submit it to another of
PR(A-E), since you should have submitted it to the most appropriate one in
the first place, which should be the only one of PR(A-E) the paper should
appear in. Think of PR(A-E) as 5 sections of one giant journal.
AIP told me it does not
publish articles with original research.
That is also not true, though since all published work needs to be
original, I don't know what your definition of "original" is.
It is true, the American Journal of Physics told me I should submit my
work to a "research journal."
So your original statement was incorrect. Yes, AJP is a physics education
journal. It certainly isn't the place to try to publish groundbreaking
radical research overthrowing centuries of established physics.
You did know that AIP publishes many journals, most of which are for
original research?
You did know that AIP isn't actually the publisher of AJP? Look at the
journal webpage, and you will see that it's published by the American
Association of Physics Teachers.
Have you considered hiring someone to review your paper? That's what
book authors do.
I don't have that kind of money.
So, instead of wasting time on usenet, or other playing on internet or
www, why not do some part time work and earn some money so that you _do_
have that kind of money?
Or if you're only willing to pay for free advice, post the paper on www
and ask for comments. Of course, this will only be useful if you're
willing to pay attention to the worthwhile comments that you get.
--
T
.
|
|
|
| User: "Peter" |
|
| Title: Re: Conservation of angular momentum |
01 Jun 2007 04:38:28 PM |
|
|
On Jun 1, 4:25 pm, "Timo A. Nieminen" <t...@physics.uq.edu.au> wrote:
On Fri, 1 Jun 2007, Peter wrote:
On May 31, 6:42 pm, PD <TheDraperFam...@gmail.com> wrote:
On May 31, 4:56 pm, Peter <Poakfi...@msn.com> wrote:
Physical Review told me that once a manuscript is rejected by one
journal, it cannot be submitted to any other.
That is not true.
It is, I can assure you.
No. Some publishers have policies that if a paper is rejected by one of
_their_ journals, it can't be submitted to another of _their_ journals. So
try another publisher. APS publishes, what, about 8 journals? A small,
small (but influential) fraction of the physics journals worldwide.
It isn't even true that an article rejected by one APS journal can't be
submitted to another APS journal. Rejection by PRL is often followed by
submission to PR(A-E). The APS website is even set up to make it easy to
do so. If rejected by PR(A-E), then you shouldn't submit it to another of
PR(A-E), since you should have submitted it to the most appropriate one in
the first place, which should be the only one of PR(A-E) the paper should
appear in. Think of PR(A-E) as 5 sections of one giant journal.
AIP told me it does not
publish articles with original research.
That is also not true, though since all published work needs to be
original, I don't know what your definition of "original" is.
It is true, the American Journal of Physics told me I should submit my
work to a "research journal."
So your original statement was incorrect. Yes, AJP is a physics education
journal. It certainly isn't the place to try to publish groundbreaking
radical research overthrowing centuries of established physics.
You did know that AIP publishes many journals, most of which are for
original research?
You did know that AIP isn't actually the publisher of AJP? Look at the
journal webpage, and you will see that it's published by the American
Association of Physics Teachers.
Have you considered hiring someone to review your paper? That's what
book authors do.
I don't have that kind of money.
So, instead of wasting time on usenet, or other playing on internet or
www, why not do some part time work and earn some money so that you _do_
have that kind of money?
Or if you're only willing to pay for free advice, post the paper on www
and ask for comments. Of course, this will only be useful if you're
willing to pay attention to the worthwhile comments that you get.
Thanks for the advice, but it does not apply due to my personal
situation.
Post it in WW what?
Peter
Peter
.
|
|
|
| User: "PD" |
|
| Title: Re: Conservation of angular momentum |
01 Jun 2007 05:17:15 PM |
|
|
On Jun 1, 4:38 pm, Peter <Poakfi...@msn.com> wrote:
Thanks for the advice, but it does not apply due to my personal
situation.
Post it in WW what?
Peter
Sign up for a free blog site on MySpace or Blogger.com and post your
paper there.
PD
.
|
|
|
| User: "Peter" |
|
| Title: Re: Conservation of angular momentum |
01 Jun 2007 05:33:55 PM |
|
|
On Jun 1, 6:17 pm, PD <TheDraperFam...@gmail.com> wrote:
On Jun 1, 4:38 pm, Peter <Poakfi...@msn.com> wrote:
Thanks for the advice, but it does not apply due to my personal
situation.
Post it in WW what?
Peter
Sign up for a free blog site on MySpace or Blogger.com and post your
paper there.
PD
Thanks. Can I include figures and equations there? Do physicists
frequent the site?
Peter
.
|
|
|
| User: "Eric Gisse" |
|
| Title: Re: Conservation of angular momentum |
01 Jun 2007 07:21:24 PM |
|
|
On Jun 1, 3:33 pm, Peter <Poakfi...@msn.com> wrote:
On Jun 1, 6:17 pm, PD <TheDraperFam...@gmail.com> wrote:
On Jun 1, 4:38 pm, Peter <Poakfi...@msn.com> wrote:
Thanks for the advice, but it does not apply due to my personal
situation.
Post it in WW what?
Peter
Sign up for a free blog site on MySpace or Blogger.com and post your
paper there.
PD
Thanks. Can I include figures and equations there? Do physicists
frequent the site?
Peter
....no, and they won't care that someone is misunderstanding freshman
physics.
.
|
|
|
|
| User: "PD" |
|
| Title: Re: Conservation of angular momentum |
02 Jun 2007 10:19:47 AM |
|
|
On Jun 1, 5:33 pm, Peter <Poakfi...@msn.com> wrote:
On Jun 1, 6:17 pm, PD <TheDraperFam...@gmail.com> wrote:
On Jun 1, 4:38 pm, Peter <Poakfi...@msn.com> wrote:
Thanks for the advice, but it does not apply due to my personal
situation.
Post it in WW what?
Peter
Sign up for a free blog site on MySpace or Blogger.com and post your
paper there.
PD
Thanks. Can I include figures and equations there? Do physicists
frequent the site?
Of course you can. Whether physicists frequent the site is up to you.
There are very few physicists that frequent this newsgroup, so you're
certainly not doing better here.
PD
.
|
|
|
| User: "Peter" |
|
| Title: Re: Conservation of angular momentum |
04 Jun 2007 06:06:58 AM |
|
|
On Jun 2, 11:19 am, PD <TheDraperFam...@gmail.com> wrote:
On Jun 1, 5:33 pm, Peter <Poakfi...@msn.com> wrote:
On Jun 1, 6:17 pm, PD <TheDraperFam...@gmail.com> wrote:
On Jun 1, 4:38 pm, Peter <Poakfi...@msn.com> wrote:
Thanks for the advice, but it does not apply due to my personal
situation.
Post it in WW what?
Peter
Sign up for a free blog site on MySpace or Blogger.com and post your
paper there.
PD
Thanks. Can I include figures and equations there? Do physicists
frequent the site?
Of course you can. Whether physicists frequent the site is up to you.
There are very few physicists that frequent this newsgroup, so you're
certainly not doing better here.
PD-
Thanks for the information.
Peter
.
|
|
|
|
|
| User: "Sam Wormley" |
|
| Title: Re: Conservation of angular momentum |
01 Jun 2007 10:40:06 PM |
|
|
Peter wrote:
On Jun 1, 6:17 pm, PD <TheDraperFam...@gmail.com> wrote:
On Jun 1, 4:38 pm, Peter <Poakfi...@msn.com> wrote:
Thanks for the advice, but it does not apply due to my personal
situation.
Post it in WW what?
Peter
Sign up for a free blog site on MySpace or Blogger.com and post your
paper there.
PD
Thanks. Can I include figures and equations there? Do physicists
frequent the site?
Peter
Peter, if you want to be taken seriously, you're going to have to
learn some real physics.
A Physics Booklist: Recommendations from the Net
http://math.ucr.edu/home/baez/physics/Administrivia/booklist.html
.
|
|
|
| User: "Peter" |
|
| Title: Re: Conservation of angular momentum |
02 Jun 2007 08:19:44 AM |
|
|
On Jun 1, 11:40 pm, Sam Wormley <sworml...@mchsi.com> wrote:
Peter wrote:
On Jun 1, 6:17 pm, PD <TheDraperFam...@gmail.com> wrote:
On Jun 1, 4:38 pm, Peter <Poakfi...@msn.com> wrote:
Thanks for the advice, but it does not apply due to my personal
situation.
Post it in WW what?
Peter
Sign up for a free blog site on MySpace or Blogger.com and post your
paper there.
PD
Thanks. Can I include figures and equations there? Do physicists
frequent the site?
Peter
Peter, if you want to be taken seriously, you're going to have to
learn some real physics.
A Physics Booklist: Recommendations from the Net
http://math.ucr.edu/home/baez/physics/Administrivia/booklist.html- Hide quoted text -
I learned classical mechanics. The problem is not my lack of
knowledge, it is with some fundamental concepts; for instance, we all
know there cannot be the perpetual motion machine, that is, a machine
that would work without an energy input. That means there cannot be
any activity without an energy input. Do you agree?
Peter
.
|
|
|
| User: "Greg Neill" |
|
| Title: Re: Conservation of angular momentum |
02 Jun 2007 01:33:59 PM |
|
|
"Peter" <Poakfield@msn.com> wrote in message
news:1180790384.585936.134740@g4g2000hsf.googlegroups.com...
I learned classical mechanics. The problem is not my lack of
knowledge, it is with some fundamental concepts; for instance, we all
know there cannot be the perpetual motion machine, that is, a machine
that would work without an energy input. That means there cannot be
any activity without an energy input. Do you agree?
Define "activity". Two bodies in mutual orbit require
no energy input in order to remain orbiting. Do you
not consider orbital motion "activity"?
.
|
|
|
|
| User: "Sam Wormley" |
|
| Title: Re: Conservation of angular momentum |
02 Jun 2007 10:06:05 AM |
|
|
Peter wrote:
I learned classical mechanics. The problem is not my lack of
knowledge, it is with some fundamental concepts; for instance, we all
know there cannot be the perpetual motion machine, that is, a machine
that would work without an energy input. That means there cannot be
any activity without an energy input. Do you agree?
Peter
If you had learned classical mechanics, you would not be confused about
angular momentum, momentum, energy, the conservation laws and vector
calculus.
.
|
|
|
| User: "Peter" |
|
| Title: Re: Conservation of angular momentum |
02 Jun 2007 11:13:06 AM |
|
|
On Jun 2, 11:06 am, Sam Wormley <sworml...@mchsi.com> wrote:
Peter wrote:
I learned classical mechanics. The problem is not my lack of
knowledge, it is with some fundamental concepts; for instance, we all
know there cannot be the perpetual motion machine, that is, a machine
that would work without an energy input. That means there cannot be
any activity without an energy input. Do you agree?
Peter
If you had learned classical mechanics, you would not be confused about
angularmomentum,momentum, energy, theconservationlaws and vector
calculus.
I am not confused at all. I understand them very well. That is why I
think the concept of angular momentum is wrong.
Peter
.
|
|
|
| User: "Sam Wormley" |
|
| Title: Re: Conservation of angular momentum |
02 Jun 2007 01:44:57 PM |
|
|
Peter wrote:
On Jun 2, 11:06 am, Sam Wormley <sworml...@mchsi.com> wrote:
If you had learned classical mechanics, you would not be confused about
angularmomentum,momentum, energy, theconservationlaws and vector
calculus.
I am not confused at all. I understand them very well. That is why I
think the concept of angular momentum is wrong.
Peter
Angular momentum (lay level)
http://en.wikipedia.org/wiki/Angular_momentum
"In physics, the angular momentum of an object rotating about some
reference point is the measure of the extent to which the object will
continue to rotate about that point unless acted upon by an external
torque.
"In particular, if a point mass rotates about an axis, then the
angular momentum with respect to a point on the axis is related to
the mass of the object, the velocity and the distance of the mass to
the axis.
"Angular momentum is important in physics because it is a conserved
quantity: a system's angular momentum stays constant unless an
external torque acts on it. Torque is the rate at which angular
momentum is transferred in or out of the system. When a rigid body
rotates, its resistance to a change in its rotational motion is
measured by its moment of inertia.
"Angular momentum is an important concept in both physics and
engineering, with numerous applications. For example, the kinetic
energy stored in a massive rotating object such as a flywheel is
proportional to the square of the angular momentum.
"Conservation of angular momentum also explains many phenomena in
sports and nature".
Relationship between force (F), torque (?), and momentum vectors
(p and L) in a rotating system.
http://upload.wikimedia.org/wikipedia/commons/0/09/Torque_animation.gif
.
|
|
|
| User: "Peter" |
|
| Title: Re: Conservation of angular momentum |
04 Jun 2007 08:37:40 AM |
|
|
On Jun 2, 2:44 pm, Sam Wormley <sworml...@mchsi.com> wrote:
Peter wrote:
On Jun 2, 11:06 am, Sam Wormley <sworml...@mchsi.com> wrote:
If you had learned classical mechanics, you would not be confused about
angularmomentum,momentum, energy, theconservationlaws and vector
calculus.
I am not confused at all. I understand them very well. That is why I
think the concept ofangularmomentumis wrong.
Peter
Angularmomentum(lay level)
http://en.wikipedia.org/wiki/Angular_momentum
"In physics, theangularmomentumof an object rotating about some
reference point is the measure of the extent to which the object will
continue to rotate about that point unless acted upon by an external
torque.
"In particular, if a point mass rotates about an axis, then the
angularmomentumwith respect to a point on the axis is related to
the mass of the object, the velocity and the distance of the mass to
the axis.
"Angularmomentumis important in physics because it is a conserved
quantity: a system'sangularmomentumstays constant unless an
external torque acts on it. Torque is the rate at whichangular
momentumis transferred in or out of the system. When a rigid body
rotates, its resistance to a change in its rotational motion is
measured by its moment of inertia.
"Angularmomentumis an important concept in both physics and
engineering, with numerous applications. For example, the kinetic
energy stored in a massive rotating object such as a flywheel is
proportional to the square of theangularmomentum.
"Conservationofangularmomentumalso explains many phenomena in
sports and nature".
Relationship between force (F), torque (?), andmomentumvectors
(p and L) in a rotating system.
http://upload.wikimedia.org/wikipedia/commons/0/09/Torque_animation.gif
The following summarizes my views:
There is only one law of conservation of momentum mv, instead of the
two laws now generally acknowledged. The momentum of an object is
conserved if no net external force acts on it; if a net external force
acts in a direction perpendicular to that of its motion, the direction
of its velocity changes, but not its magnitude; if a net external
force acts in the direction of its motion, the magnitude of its
momentum changes, but not its direction. The momentum of an extended
object in rectilinear motion is the sum of the momenta of its
constituent particles. The magnitude of the momentum of an extended
object in rotational motion is the sum of the magnitudes of the
momenta of its constituent particles. Momentum is a vector, and a
vector is rectilinear, as is the force that generates it. We show the
concept of angular momentum is faulty, and leads to gross disagreement
between theoretical and experimental results.
.
|
|
|
| User: "Ben C" |
|
| Title: Re: Conservation of angular momentum |
04 Jun 2007 11:32:57 AM |
|
|
On 2007-06-04, Peter <Poakfield@msn.com> wrote:
[...]
The following summarizes my views:
There is only one law of conservation of momentum mv, instead of the
two laws now generally acknowledged. The momentum of an object is
conserved if no net external force acts on it; if a net external force
acts in a direction perpendicular to that of its motion, the direction
of its velocity changes, but not its magnitude;
You can change the magnitude with a force perpendicular to the direction
of motion.
if a net external force acts in the direction of its motion, the
magnitude of its momentum changes, but not its direction.
Correct.
The momentum of an extended object in rectilinear motion is the sum of
the momenta of its constituent particles. The magnitude of the
momentum of an extended object in rotational motion is the sum of the
magnitudes of the momenta of its constituent particles. Momentum is a
vector, and a vector is rectilinear, as is the force that generates
it. We show the concept of angular momentum is faulty, and leads to
gross disagreement between theoretical and experimental results.
You haven't shown that the concept of angular momentum is faulty; you've
only shown that you don't understand it. But that's nothing to be
ashamed of: lots of people don't understand it even if they know how to
apply it and think they do. I don't claim to understand it myself. You
need to present your analysis of the puck-hits-lever experiment, that
shows that the puck stops with a lever of 6x the mass of the puck and
assumes no energy loss, and then we can show you where you're going
wrong.
.
|
|
|
| User: "Peter" |
|
| Title: Re: Conservation of angular momentum |
04 Jun 2007 03:35:28 PM |
|
|
On Jun 4, 12:32 pm, Ben C <spams...@spam.eggs> wrote:
On 2007-06-04, Peter <Poakfi...@msn.com> wrote:
[...]
The following summarizes my views:
There is only one law ofconservationofmomentummv, instead of the
two laws now generally acknowledged. Themomentumof an object is
conserved if no net external force acts on it; if a net external force
acts in a direction perpendicular to that of its motion, the direction
of its velocity changes, but not its magnitude;
You can change the magnitude with a force perpendicular to the direction
of motion.
if a net external force acts in the direction of its motion, the
magnitude of itsmomentumchanges, but not its direction.
Correct.
Themomentumof an extended object in rectilinear motion is the sum of
the momenta of its constituent particles. The magnitude of the
momentumof an extended object in rotational motion is the sum of the
magnitudes of the momenta of its constituent particles.Momentumis a
vector, and a vector is rectilinear, as is the force that generates
it. We show the concept ofangularmomentumis faulty, and leads to
gross disagreement between theoretical and experimental results.
You haven't shown that the concept ofangularmomentumis faulty; you've
only shown that you don't understand it. But that's nothing to be
ashamed of: lots of people don't understand it even if they know how to
apply it and think they do. I don't claim to understand it myself. You
need to present your analysis of the puck-hits-lever experiment, that
shows that the puck stops with a lever of 6x the mass of the puck and
assumes no energy loss, and then we can show you where you're going
wrong.
I say it is impossible for kinetic energy to be conserved when a point
object of mass m collides with an extended object of mass 6m, and
transfers all its momentum to it. It would be like saying that if a
point object of mass m collides with another point object of mass 6m,
and transfers all its momentum to it, energy can be conserved. There
is no problem with conservation of momentum, because mv = 6m(v/6), but
for kinetic energy to be conserved at the same time it is absolutely
impossible.
Peter
.
|
|
|
| User: "Greg Neill" |
|
| Title: Re: Conservation of angular momentum |
04 Jun 2007 05:10:31 PM |
|
|
"Peter" <Poakfield@msn.com> wrote in message
news:1180989328.327219.190030@o5g2000hsb.googlegroups.com...
I say it is impossible for kinetic energy to be conserved when a point
object of mass m collides with an extended object of mass 6m, and
transfers all its momentum to it. It would be like saying that if a
point object of mass m collides with another point object of mass 6m,
and transfers all its momentum to it, energy can be conserved. There
is no problem with conservation of momentum, because mv = 6m(v/6), but
for kinetic energy to be conserved at the same time it is absolutely
impossible.
Kinetic energy is not an integral of the motion. That is,
it is not guaranteed to be conserved. Total energy is
conserved. Total energy can comprise Kinetic, Potential,
and/or Rotational energy, as well as energy stored in
other sorts of fields such as electromagnetic fields.
Total energy can exchange between all these forms of
"currency".
The integrals of the motion known as linear and angular
momentum, on the other had, are strictly conserved
quantities that never exchange forms.
.
|
|
|
| User: "Peter" |
|
| Title: Re: Conservation of angular momentum |
05 Jun 2007 08:25:16 AM |
|
|
On Jun 4, 6:10 pm, "Greg Neill" <gneill...@OVEsympatico.ca> wrote:
"Peter" <Poakfi...@msn.com> wrote in message
news:1180989328.327219.190030@o5g2000hsb.googlegroups.com...
I say it is impossible for kinetic energy to be conserved when a point
object of mass m collides with an extended object of mass 6m, and
transfers all itsmomentumto it. It would be like saying that if a
point object of mass m collides with another point object of mass 6m,
and transfers all itsmomentumto it, energy can be conserved. There
is no problem withconservationofmomentum, because mv = 6m(v/6), but
for kinetic energy to be conserved at the same time it is absolutely
impossible.
Kinetic energy is not an integral of the motion. That is,
it is not guaranteed to be conserved. Total energy is
conserved. Total energy can comprise Kinetic, Potential,
and/or Rotational energy, as well as energy stored in
other sorts of fields such as electromagnetic fields.
Total energy can exchange between all these forms of
"currency".
The integrals of the motion known as linear andangularmomentum, on the other had, are strictly conserved
quantities that never exchange forms.
Didn't we agree linear and angular momentum can be converted into each
other? What kind of momentum is generated in an internal combustion
engine when a mixture of air and gas explodes?
Peter
.
|
|
|
| User: "Greg Neill" |
|
| Title: Re: Conservation of angular momentum |
05 Jun 2007 08:49:10 AM |
|
|
"Peter" <Poakfield@msn.com> wrote in message
news:1181049916.315893.105170@n4g2000hsb.googlegroups.com...
Didn't we agree linear and angular momentum can be converted into each
other? What kind of momentum is generated in an internal combustion
engine when a mixture of air and gas explodes?
No, we did not agree to that. Linear and angular momentum
are conserved separately.
When a piston turns a wheel, there are torques that
impart the angular momentum to the wheel and to
the frame that the piston is mounted to. Note how a
car engine twists in its mount when it is revved. The
angular momentum imparted via the mount to the chassis
to the ground is not noticed by the observer who is
standing on the ground because the resulting angular
velocities are far too minute (due to very large moment
of inertia of the Earth).
.
|
|
|
| User: "Peter" |
|
| Title: Re: Conservation of angular momentum |
05 Jun 2007 04:09:04 PM |
|
|
On Jun 5, 9:49 am, "Greg Neill" <gneill...@OVEsympatico.ca> wrote:
"Peter" <Poakfi...@msn.com> wrote in message
news:1181049916.315893.105170@n4g2000hsb.googlegroups.com...
Didn't we agree linear andangularmomentumcan be converted into each
other? What kind ofmomentumis generated in an internal combustion
engine when a mixture of air and gas explodes?
No, we did not agree to that. Linear andangularmomentum
are conserved separately.
When a piston turns a wheel, there are torques that
impart theangularmomentumto the wheel and to
the frame that the piston is mounted to. Note how a
car engine twists in its mount when it is revved. Theangularmomentumimparted via the mount to the chassis
to the ground is not noticed by the observer who is
standing on the ground because the resultingangular
velocities are far too minute (due to very large moment
of inertia of the Earth).
Yes, that is right, the wheels have angular momentum, but the
particles of the exploding mixture have only linear momentum, which
the engine converts into angular momentum. Don't you think so?
Peter
.
|
|
|
| User: "Greg Neill" |
|
| Title: Re: Conservation of angular momentum |
05 Jun 2007 04:27:39 PM |
|
|
"Peter" <Poakfield@msn.com> wrote in message
news:1181077744.357412.266400@h2g2000hsg.googlegroups.com...
On Jun 5, 9:49 am, "Greg Neill" <gneill...@OVEsympatico.ca> wrote:
When a piston turns a wheel, there are torques that
impart theangularmomentumto the wheel and to
the frame that the piston is mounted to. Note how a
car engine twists in its mount when it is revved. The
angular momentum imparted via the mount to the chassis
to the ground is not noticed by the observer who is
standing on the ground because the resultingangular
velocities are far too minute (due to very large moment
of inertia of the Earth).
Yes, that is right, the wheels have angular momentum, but the
particles of the exploding mixture have only linear momentum, which
the engine converts into angular momentum. Don't you think so?
No. In what frame of reference is the momentum of
all of the particles only linear? None, unless the
particles are in a single-file beam and the observer
is directly along the trajectory.
An analogy to a linear example might help you. Suppose
there is a sphere in space at rest with respect to some
observer. An internal explosion severs the sphere into
two equal halves which proceed to fly apart with equal
velocity in opposite direction. Clearly kinetic energy
has been added to the system (via the release of energy
in the explosion). Each half now has some momentum
that it didn't have before. But the important thing is
that the sum of the momenta (which are vector quantities)
is still zero. The same is true for the sum of the
angular momenta thus engendered.
In a similar fashion, the explosions in the cylinder that
power the internal combustion engine result in no net
change in angular momentum for the overall system.
.
|
|
|
| User: "Peter" |
|
| Title: Re: Conservation of angular momentum |
06 Jun 2007 07:44:51 AM |
|
|
On Jun 5, 5:27 pm, "Greg Neill" <gneill...@OVEsympatico.ca> wrote:
"Peter" <Poakfi...@msn.com> wrote in message
news:1181077744.357412.266400@h2g2000hsg.googlegroups.com...
On Jun 5, 9:49 am, "Greg Neill" <gneill...@OVEsympatico.ca> wrote:
When a piston turns a wheel, there are torques that
impart theangularmomentumto the wheel and to
the frame that the piston is mounted to. Note how a
car engine twists in its mount when it is revved. The
angularmomentumimparted via the mount to the chassis
to the ground is not noticed by the observer who is
standing on the ground because the resultingangular
velocities are far too minute (due to very large moment
of inertia of the Earth).
Yes, that is right, the wheels haveangularmomentum, but the
particles of the exploding mixture have only linearmomentum, which
the engine converts intoangularmomentum. Don't you think so?
No. In what frame of reference is themomentumof
all of the particles only linear? None, unless the
particles are in a single-file beam and the observer
is directly along the trajectory.
An analogy to a linear example might help you. Suppose
there is a sphere in space at rest with respect to some
observer. An internal explosion severs the sphere into
two equal halves which proceed to fly apart with equal
velocity in opposite direction. Clearly kinetic energy
has been added to the system (via the release of energy
in the explosion). Each half now has somemomentum
that it didn't have before. But the important thing is
that the sum of the momenta (which are vector quantities)
is still zero. The same is true for the sum of theangularmomenta thus engendered.
In a similar fashion, the explosions in the cylinder that
power the internal combustion engine result in no net
change inangularmomentumfor the overall system.
You are right. It seems the total momentum of the universe is zero.
But moving cars can have both linear and angular momentum, right?
To get back to topic, do you agree that levers of different mass can
have the same angular momentum? Do you think levers with different
mass, which have the same angular momentum, can have the same kinetic
energy?
Peter
.
|
|
|
|
|
| User: "Ben C" |
|
| Title: Re: Conservation of angular momentum |
05 Jun 2007 04:16:57 PM |
|
|
On 2007-06-05, Peter <Poakfield@msn.com> wrote:
On Jun 5, 9:49 am, "Greg Neill" <gneill...@OVEsympatico.ca> wrote:
"Peter" <Poakfi...@msn.com> wrote in message
news:1181049916.315893.105170@n4g2000hsb.googlegroups.com...
Didn't we agree linear andangularmomentumcan be converted into each
other? What kind ofmomentumis generated in an internal combustion
engine when a mixture of air and gas explodes?
No, we did not agree to that. Linear andangularmomentum
are conserved separately.
When a piston turns a wheel, there are torques that
impart theangularmomentumto the wheel and to
the frame that the piston is mounted to. Note how a
car engine twists in its mount when it is revved. Theangularmomentumimparted via the mount to the chassis
to the ground is not noticed by the observer who is
standing on the ground because the resultingangular
velocities are far too minute (due to very large moment
of inertia of the Earth).
Yes, that is right, the wheels have angular momentum, but the
particles of the exploding mixture have only linear momentum
No, they have angular momentum measured with respect to any origin you
like so long as that origin doesn't intersect the path of the pistons.
which the engine converts into angular momentum. Don't you think so?
The crankshaft converts linear motion into circular motion. This is not
to be confused with "converting linear momentum into angular momentum".
Angular momentum is NOT the same thing as circular motion.
.
|
|
|
| User: "Peter" |
|
| Title: Re: Conservation of angular momentum |
06 Jun 2007 07:35:25 AM |
|
|
On Jun 5, 5:16 pm, Ben C <spams...@spam.eggs> wrote:
On 2007-06-05, Peter <Poakfi...@msn.com> wrote:
On Jun 5, 9:49 am, "Greg Neill" <gneill...@OVEsympatico.ca> wrote:
"Peter" <Poakfi...@msn.com> wrote in message
news:1181049916.315893.105170@n4g2000hsb.googlegroups.com...
Didn't we agree linear andangularmomentumcan be converted into each
other? What kind ofmomentumis generated in an internal combustion
engine when a mixture of air and gas explodes?
No, we did not agree to that. Linear andangularmomentum
are conserved separately.
When a piston turns a wheel, there are torques that
impart theangularmomentumto the wheel and to
the frame that the piston is mounted to. Note how a
car engine twists in its mount when it is revved. Theangularmomentumimparted via the mount to the chassis
to the ground is not noticed by the observer who is
standing on the ground because the resultingangular
velocities are far too minute (due to very large moment
of inertia of the Earth).
Yes, that is right, the wheels haveangularmomentum, but the
particles of the exploding mixture have only linearmomentum
No, they haveangularmomentummeasured with respect to any origin you
like so long as that origin doesn't intersect the path of the pistons.
which the engine converts intoangularmomentum. Don't you think so?
The crankshaft converts linear motion into circular motion. This is not
to be confused with "converting linearmomentumintoangularmomentum".
Angularmomentumis NOT the same thing as circular motion.-
Linear motion has linear momentum, angular motion has angular momentum
no?
To get back to topic, do you agree that levers of different mass can
have the same angular momentum? Do you think levers with different
mass, which have the same angular momentum, can have the same kinetic
energy?
Peter
.
|
|
|
| User: "Greg Neill" |
|
| Title: Re: Conservation of angular momentum |
06 Jun 2007 07:57:43 AM |
|
|
"Peter" <Poakfield@msn.com> wrote in message
news:1181133325.171981.124050@q69g2000hsb.googlegroups.com...
Linear motion has linear momentum, angular motion has angular momentum
no?
Linear motion has angular momentum too, depending upon the
origin of the frame of reference chosen.
To get back to topic, do you agree that levers of different mass can
have the same angular momentum? Do you think levers with different
mass, which have the same angular momentum, can have the same kinetic
energy?
Why are you confused about this?
Angular momentum: L = I*w
Rotational KE: KE = (1/2)*I*w^2
I, the moment of inertia, depends upon the mass and its
geometrical distribution. You can always vary w to make
the values of L or KR take on any values you like.
.
|
|
|
| User: "Peter" |
|
| Title: Re: Conservation of angular momentum |
06 Jun 2007 02:31:04 PM |
|
|
On Jun 6, 8:57 am, "Greg Neill" <gneill...@OVEsympatico.ca> wrote:
"Peter" <Poakfi...@msn.com> wrote in message
news:1181133325.171981.124050@q69g2000hsb.googlegroups.com...
Linear motion has linearmomentum,angularmotion hasangularmomentum
no?
Linear motion hasangularmomentumtoo, depending upon the
origin of the frame of reference chosen.
To get back to topic, do you agree that levers of different mass can
have the sameangularmomentum? Do you think levers with different
mass, which have the sameangularmomentum, can have the same kinetic
energy?
Why are you confused about this?
Angularmomentum: L = I*w
Rotational KE: KE = (1/2)*I*w^2
I, the moment of inertia, depends upon the mass and its
geometrical distribution. You can always vary w to make
the values of L or KR take on any values you like.
Maybe the question should have been: do you agree that levers with the
same dimensions and different masses (different materials) can have
the same angular momentum? Do you think levers with the same
dimensions and different masses, which have the same angular momentum,
can have the same kinetic energy?
Peter
.
|
|
|
| User: "Greg Neill" |
|
| Title: Re: Conservation of angular momentum |
06 Jun 2007 03:44:10 PM |
|
|
"Peter" <Poakfield@msn.com> wrote in message
news:1181158264.308301.281950@x35g2000prf.googlegroups.com...
Maybe the question should have been: do you agree that levers with the
same dimensions and different masses (different materials) can have
the same angular momentum?
Same dimensions and different masses ===> different moments
of inertia (unless you allow non-uniform density to adjust
them). So to have the same angular momentum you simply
adjust the angular velocities:
I1 =/= I2 (not equal)
I1*w1 = I2*w2
So, yes.
Do you think levers with the same
dimensions and different masses, which have the same angular momentum,
can have the same kinetic energy?
Now you want:
I1 =/= I2 (unequal moments of inertia)
I1*w1 = I2*w2 (equal angular momenta)
(1/2)*I1*w1^2 = (1/2)*I2*w2^2 (equal rotational kinetic energies)
This can only hold if w1 = w2 = 0 (angular velocities
are zero so that angular momenta are zero.
However, if you include linear kinetic energy too, then
you can adjust the translational velocities to balance
the equations. That is,
(1/2)[ I1*w1^2 + m1*v1^2 ] = (1/2)[ I2*w2^2 + m2*v2^2 ]
So the answer is NO if the levers are rotating and not
translating, and YES if one or both are also allowed to
translate (so that the total kinetic energy is the sum
of the rotational and linear translational energies).
.
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
Related Articles |
|
|
