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The introductory paragraph is somewhat obscure and is not meaningful from a lay perspective; this section should give a good physical insight into momentum and why it is important, not simply give a mathematical definition and some scientific statements which happen to be true. Metsfanmax ( talk) 18:59, 2 July 2009 (UTC)
I studied College Physics for a year in the 1980s, and a lot of the introduction was opaque to me. I can only imagine the casual reader is not well served by this. Seems the technical experts never seem to care about the readability of introductions. I agree the main body of the article can be more technical. 2601:281:CB00:2A0:FD0B:480B:BCA7:85F8 ( talk) 04:56, 30 December 2017 (UTC)
We had a complaint at WikiProject Physics (see Simple explanations, please) that this article is not easy for someone with no background in physics to read. There are some good efforts in this article to explain things simply, but often they come after more difficult concepts like frame dependence or Noether's theorem. I am reorganizing the article to put more difficult material later. RockMagnetist ( talk) 16:27, 22 July 2012 (UTC)
The section Momentum#History of the concept has the appearance of original research, with many judgements stated without backing by an independent source. That is particularly true of the discussion of Newton's mechanics, with statements like this: "The extent to which Isaac Newton contributed to the concept has been much debated. The answer is apparently nothing, except to state more fully and with better mathematics what was already known. ". There is a lot of good material here, and I hope someone can find suitable third-party sources for it. RockMagnetist ( talk) 16:44, 30 July 2012 (UTC)
The article Kinetic momentum is based on a backwards interpretation. Being equal to mv, kinetic momentum does not contain the vector potential, while the canonical momentum does. It is also known as mechanical momentum (see the Goldstein and Jackson references in the first paragraph of Momentum#Generalized momentum). Since that is the main subject of the article momentum, this article should be merged into Momentum. RockMagnetist ( talk) 21:45, 1 August 2012 (UTC)
As far as I know, the following is the correct terminology (copied from kinetic momentum):
which fits in with the linked definition by Quondum:
(difference between total/canonical and potential momenta). But clearly RockMagnetist has a point: "kinetic momentum" mv is the subject of this article. The "canonical momentum" P is the generalized momentum found from Lagrangian mechanics:
Also the worded description does seem to indicate the EM field energy:
which is not the same as the "potential momentum" eA, pointed out by Quondum... So a merge would be fine. Maschen ( talk) 01:37, 15 August 2012 (UTC)
I will do this by tomorrow if no-one else does. There has been plenty of time for people to object or do the merge themselves. Aside from that I will stay out of the article, for reasons below, and leave it to others thenfrom... Maschen ( talk) 22:05, 6 September 2012 (UTC)
I removed the section on analogies with mass and heat transfer. It is misleading, because the viscosity law of a Newtonian fluid is not an equation for momentum transfer, although it does contribute to the equation for conservation of momentum. Similarly, the relevant analogues for heat and mass are also conservation equations. RockMagnetist ( talk) 16:57, 4 August 2012 (UTC)
A general expression for Newton's law does apply for a system with variable mass by treating mass as a variable wrt time:
So the statement:
doesn't make much sense to me.
Maschen (
talk)
15:56, 4 September 2012 (UTC)
On the whole, I'm o.k. with "does not exchange matter with its surroundings". Pedagogically, I prefer a statement about variable mass that is true for relativity as well, but your statement is simple and clear. And I like the reference. So I'll leave it the way it is. RockMagnetist ( talk) 18:21, 4 September 2012 (UTC)
In the animation, the top "box" covers more ground than the bottom one does. Further, shouldn't they always meet in the middle? I was lost for a second trying to figure out just what was trying to be taught to me because of this. I'd propose the v's be the same, top and bottom, and that the boxes on the bottom start at far left and far right so that they meet at the same place as the collision on the top.
Tgm1024 (
talk)
13:32, 9 September 2012 (UTC)
I made a first pass at writing a section on variable mass systems. Possible issues:
We have a difference of opinion about whether to represent vectors with upright or italic bold. I was arguing the mathematical convention mentioned in Vector notation, while Dger cites the SI rules that vector physical quantities be in italic boldface. I was able to confirm that in the NIST guide. Since this is a physics article, I would be inclined to agree with Dger. The entire article should follow the convention consistently - that shouldn't be too hard. RockMagnetist ( talk) 00:54, 14 November 2012 (UTC)
\boldsymbol
) has the advantage that Greek and Latin latters can be uniformly bold (instead of switching between \boldsymbol
and \mathbf
), and if there is a convention then it should be used, though there are many books where italic-bold isn't used...This article says that momentum is a vector. But is not it really a covector? At least generalized momentum looks like covector to me. -- Alexei Kopylov ( talk) 21:52, 23 May 2014 (UTC)
The section Momentum#Classical_electromagnetism makes a factually incorrect claim, but cites a Goldstone source to which I have no access. I would appreciate the relevant quote being given here. The section refers to classical electromagnetism, which is is Maxwell's theory. In this theory, there is no violation of Newton's law – a particle does not apply a force on another particle without a return force, it applies a force to the field, which applies a balancing force on the particle; by no mental acrobatics can this be construed as "no return force". The field, some time later, may as a result of its perturbation apply a force to another particle, again obeying Newton's law of action and reaction. Let's get this fixed. — Quondum 14:21, 13 July 2014 (UTC)
Consider, further, two charges moving (instantaneously) so as to "cross the T," i.e., one charge moving directly at the other, which in turn is moving at right angles to the first. Then the second charge exerts a nonvanishing force on the first, without experiencing any reaction force at all.
In a system involving moving charges, the forces between the charges predicted by the Biot-Savart law indeed may violate both forms of the action and reaction law.* Equations (1-23) and (1-26), and the corresponding conservation theorems, are not applicable in such cases, at least in the form here given. Usually it is then possible to find some generalization of P or L that is conserved. Thus, in an isolated system of moving charges it is the sum of the mechanical angular momentum and the electromagnetic "angular momentum" of the field that is conserved.
A thought that occurs to me is that this article is roughly built along the lines of domains of applicability – as per the diagram here – where three of the domains appear to be addressed (§Newtonian mechanics, §Relativistic mechanics and §Quantum mechanics, which I've now grouped together). The lead also introduces the topic as being "In classical mechanics ...", yet the article goes beyond this. Perhaps this should read "In physics ..."? The section §Classical electromagnetism seem to span several of the these domains, so I feel that this should be split up as subsections under the domain-of-validity headings. The phrase "classical electromagnetism" could also be avoided, as it is not clear (to me, anyway) whether it means electromagnetism in classical mechanics (hence nonrelativistic) or electromagnetism as per Maxwell (relativistic). Does this line of thought make sense? — Quondum 17:58, 16 July 2014 (UTC)
Where is the definition, I don't know what it is, but thought it was something like the tendency of an object in motion to continue in motion, Something like that would be helpful. This article is chaotic, with reams of references all over the place. There is also an assumption that beyond a certain level this concept is the property of science. but it has many every day application, not just in academics, whether grade school or beyond. Those are actually the places where if you have a reason to know this stuff you already do. — Preceding unsigned comment added by 70.27.118.120 ( talk • contribs) 2015-04-11T08:39:38
The article on the quantum momentum operator states "As it is known from classical mechanics, the momentum is the generator of translation," and "momentum" in that sentence is a link to this article. However, this momentum article does not cover the concept of "generator of translations". It would be good if someone could add this. Tpellman ( talk) 01:55, 18 May 2015 (UTC)
There is a link to angular momentum but do we need a hat note to it since this article is specifically linear momentum? RJFJR ( talk) 20:04, 7 June 2016 (UTC)
The lead has this sentence. It is not helpful, it's like saying charge conservation is implied by Maxwell's equations. But momentum conservation and charge conservation are more fundamental than the laws (which are empirical/postulate equations), and separate statements. It would be better to say Newton's laws are consistent with momentum conservation, but even then this leads to awkward issues with variable mass systems (in this article, section Momentum#Objects of variable mass), in which case you must use momentum conservation to set up the equation of motion correctly.
A stronger way to infer momentum conservation is by translation symmetries (see previous section on this talk page). Any thoughts? M ∧Ŝ c2ħε Иτlk 07:17, 10 June 2016 (UTC)
References
One of the equations in this article has been revised multiple times recently. The main issue is whether v/c should be represented by a slash,
or as a vertical fraction:
or
Those in favor of the first version are trying to maximize the size of the characters; an IP editor claims this is arbitrary and has expressed a distaste for slashes. I have two comments:
Thus, I favor the first version. The third isn't bad, but requires rather more TeX commands than a simple equation like this should need. What is your preference ? RockMagnetist( talk) 15:28, 29 June 2016 (UTC)
A fourth option would get rid of the parentheses in the first version:
RockMagnetist( talk) 15:33, 29 June 2016 (UTC)
I scanned for British spellings "our" and "ise", and came up empty. "Generalize" is used frequently, therefore I conclude the article is already in American English. JustinTime55 ( talk) 14:39, 11 August 2016 (UTC)
In the "other units" section of the information box, the article lists "ft/s" as a unit of momentum. This seems like an error; ft/s stands for feet per second, which is a unit of speed and velocity (not momentum, at least as far as I am aware). Furthermore, the text links to the page for feet per second, which makes no mention whatsoever of momentum. Should this be changed, or is there something I'm missing here? 108.20.171.228 ( talk) 22:51, 17 October 2016 (UTC)Gus Wiedey
Should be multiplied by a pound, the US Customary unit of mass. The slug is a derived unit that no one ever actually uses. John G Hasler ( talk) 23:18, 21 May 2022 (UTC)
Don’t declaration and acceleration produced during the infinitesimal contact period of time in collision affects the transfer of momentum (final velocities) of objects after collision 2001:56A:7399:1200:3078:21D0:B447:EDC6 ( talk) 05:24, 31 March 2017 (UTC)eek
After all, the balls constantly change direction (as they generally do in pendulums) which actually appears as a *violation* of the conservation law. The conservation is only true for the entire earth-pendulum system: The momentum differences are equalized by corresponding changes in earth's momentum, but since we are actually applying tangential forces to a sphere (earth) spinning with the speed of sound around its axis ... you get the picture. A good demonstration would be to put the cradle on a low-friction vehicle which will oscillate, moving back and forth, compensating the ball's momentum at each point in time.
One should **remove Newton's cradle.** 80.146.228.85 ( talk) 14:16, 24 May 2018 (UTC)
This section is biased and inaccurate on at least three points. (1) It interprets and rubbishes Descartes' contribution "This should not be read as a statement of the modern law of momentum since ... he believed that it is speed rather than velocity that is conserved." No reference is given for this interpretation and the original clearly refers to head-on collisions (as seen in the subsequent rules). See also his second law of motion in The World (Descartes), and in Descartes' Principia Philosophiae Book 2 Section 37 and 40 [1] (page 57). (2) There is no reference at all to Huygens, even though he is often quoted as the originator of the principle of conservation of momentum. This is probably due to an anglo-centric reporting of the Royal Society Proceedings of 1668. See [2] and [3] (page 229). (3) It gives all the credit to Wallis for this principle: "The first correct statement of the law of conservation of momentum was by English mathematician John Wallis in his 1670 work". No reference to this claim by a historian is given except for the original work, and then the quote that is supposed to support this claim, namely "the initial state of the body, either of rest or of motion, will persist", makes no reference to conservation and indeed already appears in works of Descartes and Galileo. In fact Wallis, Wren, and Huygens all presented the same principles in 1668 and, according to the textbook above by David C. Cassidy, Gerald Holton, and F. James Rutherford, Huygens was more complete than them. This section should be rewritten by a historian of physics. — Preceding unsigned comment added by Chrystomath2 ( talk • contribs) 15:06, 30 November 2019 (UTC)
Please, add "kinetic momentum" to the synonyms in first line. — Preceding unsigned comment added by 81.40.235.248 ( talk) 18:51, 31 August 2020 (UTC)
This
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Change "In Hamiltonian mechanics, the Lagrangian (a function of generalized coordinates and their derivatives)" to "In Hamiltonian mechanics, the Lagrangian (a function of time, generalized coordinates and their derivatives)" 178.23.234.209 ( talk) 20:38, 27 October 2020 (UTC)
There is discussion in Talk:Hamiltonian on where Hamiltonian should be directed. It seems now to direct to the classical version of Hamiltonian mechanics. Yet more often now, it is likely that the quantum mechanics version is meant. It then occurred to me that most likely momentum would direct to the classical explanation and not the quantum version, and it does seem that we have Momentum operator for the quantum version. (I might wonder why it isn't Momentum (quantum mechanics), but otherwise.) Without actually suggesting it, should all the quantum version be in its own article, with only classical here? Gah4 ( talk) 12:20, 1 November 2020 (UTC)
"Momentum is also conserved in special relativity (with a modified formula)".
This phrase misleading, it is not the momentum that has been defined in previous paragraph the one that is conserved, but the spatial components of the four-momentum.
To be clarified. — Preceding unsigned comment added by 81.40.239.244 ( talk) 12:43, 28 November 2020 (UTC)
When I type in momentum it comes to this article which is about physics but that is not why I was looking for momentum.
Whenever I hear the word momentum it has something to do with politics not physics.
This article makes no mention about the word being used in politics.
I asked that this be rectified or at least create an article around the political usage of momentum. 49.3.72.79 ( talk) 04:46, 13 February 2021 (UTC)
The article says: when bodies come in contact there is always some dissipation. Classically, it is hard to avoid some dissipation, but in quantum systems, there can only be dissipation if there are states available for energy to go into. When atoms in a gas collide, there is not normally enough energy to get one to the next available energy state. Or, one might say that atoms never collide, but instead there is repulsion from the electron cloud. But it is Fermi exclusion more than electron repulsion that keeps atoms apart. In any case, in quantum systems there is not always some dissipation. Gah4 ( talk) 18:35, 16 June 2021 (UTC)
On my iPhone 11, the introduction says "then the object's momentum p is", then shows the billiard balls with caption, then the formula floating all by itself below. If it's possible, if someone could get the formula to stick with the paragraph it would be easier to follow. Thanks. Pbackstrom ( talk) 13:53, 30 December 2021 (UTC)
following is for editing "Momentum" Page on Wikipedia.org:
NOTE : Recent research findings reported a novel equation for Momentum, which is NOT based upon mass and velocity of the body under motion but, it is based upon the mass and "frequency" of the particle under motion. You could find that research work at the DOI given below. This work is available online, for your kind information.
Research Article Title: "Kinetic Energy of a Particle Independent of its Mass & Velocity"; DOI:10.9790/4861-1501013441
So, I request you to kindly update this novel equation and derivation on Wikipedia for the benefit of the wide readers of Wikipedia.
Thank you
PS: I am suggesting the following edits for addition [from START to END, present below] into the "Momentum" Page of Wikipedia; you could add more if you wish. Related novel equation for kinetic energy is also discovered in that research work at the above DOI document. You could update it as well on the Kinetic energy page of Wikipedia.
---START of EDIT---
Novel equation for "Momentum" recently discovered by research and reported in the scientific literature is given below. This discovery was done by the Indian researcher Mr. Bhargava R. Kotur, as recorded in the above DOI document.
p = sqrt (h. n . m)
In the above equation, p - stands for the Momentum, f - is the frequency of the body or particle under motion, m - is the mass of the body, and h - is the famous Planck's constant, sqrt - stands for the mathematical function "square root";
The derivation of the above work could be found at the DOI already mentioned earlier.
--- END of EDIT --- Ganesh Siva75 ( talk) 19:28, 10 February 2023 (UTC)
Text and/or other creative content from kinetic momentum was copied or moved into momentum with this edit. The former page's history now serves to provide attribution for that content in the latter page, and it must not be deleted as long as the latter page exists. |
This article is written in American English, which has its own spelling conventions (color, defense, traveled) and some terms that are used in it may be different or absent from other varieties of English. According to the relevant style guide, this should not be changed without broad consensus. |
This
level-3 vital article is rated B-class on Wikipedia's
content assessment scale. It is of interest to the following WikiProjects: | |||||||||||||||||||||||||||||||
|
To-do list for Momentum:
|
The introductory paragraph is somewhat obscure and is not meaningful from a lay perspective; this section should give a good physical insight into momentum and why it is important, not simply give a mathematical definition and some scientific statements which happen to be true. Metsfanmax ( talk) 18:59, 2 July 2009 (UTC)
I studied College Physics for a year in the 1980s, and a lot of the introduction was opaque to me. I can only imagine the casual reader is not well served by this. Seems the technical experts never seem to care about the readability of introductions. I agree the main body of the article can be more technical. 2601:281:CB00:2A0:FD0B:480B:BCA7:85F8 ( talk) 04:56, 30 December 2017 (UTC)
We had a complaint at WikiProject Physics (see Simple explanations, please) that this article is not easy for someone with no background in physics to read. There are some good efforts in this article to explain things simply, but often they come after more difficult concepts like frame dependence or Noether's theorem. I am reorganizing the article to put more difficult material later. RockMagnetist ( talk) 16:27, 22 July 2012 (UTC)
The section Momentum#History of the concept has the appearance of original research, with many judgements stated without backing by an independent source. That is particularly true of the discussion of Newton's mechanics, with statements like this: "The extent to which Isaac Newton contributed to the concept has been much debated. The answer is apparently nothing, except to state more fully and with better mathematics what was already known. ". There is a lot of good material here, and I hope someone can find suitable third-party sources for it. RockMagnetist ( talk) 16:44, 30 July 2012 (UTC)
The article Kinetic momentum is based on a backwards interpretation. Being equal to mv, kinetic momentum does not contain the vector potential, while the canonical momentum does. It is also known as mechanical momentum (see the Goldstein and Jackson references in the first paragraph of Momentum#Generalized momentum). Since that is the main subject of the article momentum, this article should be merged into Momentum. RockMagnetist ( talk) 21:45, 1 August 2012 (UTC)
As far as I know, the following is the correct terminology (copied from kinetic momentum):
which fits in with the linked definition by Quondum:
(difference between total/canonical and potential momenta). But clearly RockMagnetist has a point: "kinetic momentum" mv is the subject of this article. The "canonical momentum" P is the generalized momentum found from Lagrangian mechanics:
Also the worded description does seem to indicate the EM field energy:
which is not the same as the "potential momentum" eA, pointed out by Quondum... So a merge would be fine. Maschen ( talk) 01:37, 15 August 2012 (UTC)
I will do this by tomorrow if no-one else does. There has been plenty of time for people to object or do the merge themselves. Aside from that I will stay out of the article, for reasons below, and leave it to others thenfrom... Maschen ( talk) 22:05, 6 September 2012 (UTC)
I removed the section on analogies with mass and heat transfer. It is misleading, because the viscosity law of a Newtonian fluid is not an equation for momentum transfer, although it does contribute to the equation for conservation of momentum. Similarly, the relevant analogues for heat and mass are also conservation equations. RockMagnetist ( talk) 16:57, 4 August 2012 (UTC)
A general expression for Newton's law does apply for a system with variable mass by treating mass as a variable wrt time:
So the statement:
doesn't make much sense to me.
Maschen (
talk)
15:56, 4 September 2012 (UTC)
On the whole, I'm o.k. with "does not exchange matter with its surroundings". Pedagogically, I prefer a statement about variable mass that is true for relativity as well, but your statement is simple and clear. And I like the reference. So I'll leave it the way it is. RockMagnetist ( talk) 18:21, 4 September 2012 (UTC)
In the animation, the top "box" covers more ground than the bottom one does. Further, shouldn't they always meet in the middle? I was lost for a second trying to figure out just what was trying to be taught to me because of this. I'd propose the v's be the same, top and bottom, and that the boxes on the bottom start at far left and far right so that they meet at the same place as the collision on the top.
Tgm1024 (
talk)
13:32, 9 September 2012 (UTC)
I made a first pass at writing a section on variable mass systems. Possible issues:
We have a difference of opinion about whether to represent vectors with upright or italic bold. I was arguing the mathematical convention mentioned in Vector notation, while Dger cites the SI rules that vector physical quantities be in italic boldface. I was able to confirm that in the NIST guide. Since this is a physics article, I would be inclined to agree with Dger. The entire article should follow the convention consistently - that shouldn't be too hard. RockMagnetist ( talk) 00:54, 14 November 2012 (UTC)
\boldsymbol
) has the advantage that Greek and Latin latters can be uniformly bold (instead of switching between \boldsymbol
and \mathbf
), and if there is a convention then it should be used, though there are many books where italic-bold isn't used...This article says that momentum is a vector. But is not it really a covector? At least generalized momentum looks like covector to me. -- Alexei Kopylov ( talk) 21:52, 23 May 2014 (UTC)
The section Momentum#Classical_electromagnetism makes a factually incorrect claim, but cites a Goldstone source to which I have no access. I would appreciate the relevant quote being given here. The section refers to classical electromagnetism, which is is Maxwell's theory. In this theory, there is no violation of Newton's law – a particle does not apply a force on another particle without a return force, it applies a force to the field, which applies a balancing force on the particle; by no mental acrobatics can this be construed as "no return force". The field, some time later, may as a result of its perturbation apply a force to another particle, again obeying Newton's law of action and reaction. Let's get this fixed. — Quondum 14:21, 13 July 2014 (UTC)
Consider, further, two charges moving (instantaneously) so as to "cross the T," i.e., one charge moving directly at the other, which in turn is moving at right angles to the first. Then the second charge exerts a nonvanishing force on the first, without experiencing any reaction force at all.
In a system involving moving charges, the forces between the charges predicted by the Biot-Savart law indeed may violate both forms of the action and reaction law.* Equations (1-23) and (1-26), and the corresponding conservation theorems, are not applicable in such cases, at least in the form here given. Usually it is then possible to find some generalization of P or L that is conserved. Thus, in an isolated system of moving charges it is the sum of the mechanical angular momentum and the electromagnetic "angular momentum" of the field that is conserved.
A thought that occurs to me is that this article is roughly built along the lines of domains of applicability – as per the diagram here – where three of the domains appear to be addressed (§Newtonian mechanics, §Relativistic mechanics and §Quantum mechanics, which I've now grouped together). The lead also introduces the topic as being "In classical mechanics ...", yet the article goes beyond this. Perhaps this should read "In physics ..."? The section §Classical electromagnetism seem to span several of the these domains, so I feel that this should be split up as subsections under the domain-of-validity headings. The phrase "classical electromagnetism" could also be avoided, as it is not clear (to me, anyway) whether it means electromagnetism in classical mechanics (hence nonrelativistic) or electromagnetism as per Maxwell (relativistic). Does this line of thought make sense? — Quondum 17:58, 16 July 2014 (UTC)
Where is the definition, I don't know what it is, but thought it was something like the tendency of an object in motion to continue in motion, Something like that would be helpful. This article is chaotic, with reams of references all over the place. There is also an assumption that beyond a certain level this concept is the property of science. but it has many every day application, not just in academics, whether grade school or beyond. Those are actually the places where if you have a reason to know this stuff you already do. — Preceding unsigned comment added by 70.27.118.120 ( talk • contribs) 2015-04-11T08:39:38
The article on the quantum momentum operator states "As it is known from classical mechanics, the momentum is the generator of translation," and "momentum" in that sentence is a link to this article. However, this momentum article does not cover the concept of "generator of translations". It would be good if someone could add this. Tpellman ( talk) 01:55, 18 May 2015 (UTC)
There is a link to angular momentum but do we need a hat note to it since this article is specifically linear momentum? RJFJR ( talk) 20:04, 7 June 2016 (UTC)
The lead has this sentence. It is not helpful, it's like saying charge conservation is implied by Maxwell's equations. But momentum conservation and charge conservation are more fundamental than the laws (which are empirical/postulate equations), and separate statements. It would be better to say Newton's laws are consistent with momentum conservation, but even then this leads to awkward issues with variable mass systems (in this article, section Momentum#Objects of variable mass), in which case you must use momentum conservation to set up the equation of motion correctly.
A stronger way to infer momentum conservation is by translation symmetries (see previous section on this talk page). Any thoughts? M ∧Ŝ c2ħε Иτlk 07:17, 10 June 2016 (UTC)
References
One of the equations in this article has been revised multiple times recently. The main issue is whether v/c should be represented by a slash,
or as a vertical fraction:
or
Those in favor of the first version are trying to maximize the size of the characters; an IP editor claims this is arbitrary and has expressed a distaste for slashes. I have two comments:
Thus, I favor the first version. The third isn't bad, but requires rather more TeX commands than a simple equation like this should need. What is your preference ? RockMagnetist( talk) 15:28, 29 June 2016 (UTC)
A fourth option would get rid of the parentheses in the first version:
RockMagnetist( talk) 15:33, 29 June 2016 (UTC)
I scanned for British spellings "our" and "ise", and came up empty. "Generalize" is used frequently, therefore I conclude the article is already in American English. JustinTime55 ( talk) 14:39, 11 August 2016 (UTC)
In the "other units" section of the information box, the article lists "ft/s" as a unit of momentum. This seems like an error; ft/s stands for feet per second, which is a unit of speed and velocity (not momentum, at least as far as I am aware). Furthermore, the text links to the page for feet per second, which makes no mention whatsoever of momentum. Should this be changed, or is there something I'm missing here? 108.20.171.228 ( talk) 22:51, 17 October 2016 (UTC)Gus Wiedey
Should be multiplied by a pound, the US Customary unit of mass. The slug is a derived unit that no one ever actually uses. John G Hasler ( talk) 23:18, 21 May 2022 (UTC)
Don’t declaration and acceleration produced during the infinitesimal contact period of time in collision affects the transfer of momentum (final velocities) of objects after collision 2001:56A:7399:1200:3078:21D0:B447:EDC6 ( talk) 05:24, 31 March 2017 (UTC)eek
After all, the balls constantly change direction (as they generally do in pendulums) which actually appears as a *violation* of the conservation law. The conservation is only true for the entire earth-pendulum system: The momentum differences are equalized by corresponding changes in earth's momentum, but since we are actually applying tangential forces to a sphere (earth) spinning with the speed of sound around its axis ... you get the picture. A good demonstration would be to put the cradle on a low-friction vehicle which will oscillate, moving back and forth, compensating the ball's momentum at each point in time.
One should **remove Newton's cradle.** 80.146.228.85 ( talk) 14:16, 24 May 2018 (UTC)
This section is biased and inaccurate on at least three points. (1) It interprets and rubbishes Descartes' contribution "This should not be read as a statement of the modern law of momentum since ... he believed that it is speed rather than velocity that is conserved." No reference is given for this interpretation and the original clearly refers to head-on collisions (as seen in the subsequent rules). See also his second law of motion in The World (Descartes), and in Descartes' Principia Philosophiae Book 2 Section 37 and 40 [1] (page 57). (2) There is no reference at all to Huygens, even though he is often quoted as the originator of the principle of conservation of momentum. This is probably due to an anglo-centric reporting of the Royal Society Proceedings of 1668. See [2] and [3] (page 229). (3) It gives all the credit to Wallis for this principle: "The first correct statement of the law of conservation of momentum was by English mathematician John Wallis in his 1670 work". No reference to this claim by a historian is given except for the original work, and then the quote that is supposed to support this claim, namely "the initial state of the body, either of rest or of motion, will persist", makes no reference to conservation and indeed already appears in works of Descartes and Galileo. In fact Wallis, Wren, and Huygens all presented the same principles in 1668 and, according to the textbook above by David C. Cassidy, Gerald Holton, and F. James Rutherford, Huygens was more complete than them. This section should be rewritten by a historian of physics. — Preceding unsigned comment added by Chrystomath2 ( talk • contribs) 15:06, 30 November 2019 (UTC)
Please, add "kinetic momentum" to the synonyms in first line. — Preceding unsigned comment added by 81.40.235.248 ( talk) 18:51, 31 August 2020 (UTC)
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Change "In Hamiltonian mechanics, the Lagrangian (a function of generalized coordinates and their derivatives)" to "In Hamiltonian mechanics, the Lagrangian (a function of time, generalized coordinates and their derivatives)" 178.23.234.209 ( talk) 20:38, 27 October 2020 (UTC)
There is discussion in Talk:Hamiltonian on where Hamiltonian should be directed. It seems now to direct to the classical version of Hamiltonian mechanics. Yet more often now, it is likely that the quantum mechanics version is meant. It then occurred to me that most likely momentum would direct to the classical explanation and not the quantum version, and it does seem that we have Momentum operator for the quantum version. (I might wonder why it isn't Momentum (quantum mechanics), but otherwise.) Without actually suggesting it, should all the quantum version be in its own article, with only classical here? Gah4 ( talk) 12:20, 1 November 2020 (UTC)
"Momentum is also conserved in special relativity (with a modified formula)".
This phrase misleading, it is not the momentum that has been defined in previous paragraph the one that is conserved, but the spatial components of the four-momentum.
To be clarified. — Preceding unsigned comment added by 81.40.239.244 ( talk) 12:43, 28 November 2020 (UTC)
When I type in momentum it comes to this article which is about physics but that is not why I was looking for momentum.
Whenever I hear the word momentum it has something to do with politics not physics.
This article makes no mention about the word being used in politics.
I asked that this be rectified or at least create an article around the political usage of momentum. 49.3.72.79 ( talk) 04:46, 13 February 2021 (UTC)
The article says: when bodies come in contact there is always some dissipation. Classically, it is hard to avoid some dissipation, but in quantum systems, there can only be dissipation if there are states available for energy to go into. When atoms in a gas collide, there is not normally enough energy to get one to the next available energy state. Or, one might say that atoms never collide, but instead there is repulsion from the electron cloud. But it is Fermi exclusion more than electron repulsion that keeps atoms apart. In any case, in quantum systems there is not always some dissipation. Gah4 ( talk) 18:35, 16 June 2021 (UTC)
On my iPhone 11, the introduction says "then the object's momentum p is", then shows the billiard balls with caption, then the formula floating all by itself below. If it's possible, if someone could get the formula to stick with the paragraph it would be easier to follow. Thanks. Pbackstrom ( talk) 13:53, 30 December 2021 (UTC)
following is for editing "Momentum" Page on Wikipedia.org:
NOTE : Recent research findings reported a novel equation for Momentum, which is NOT based upon mass and velocity of the body under motion but, it is based upon the mass and "frequency" of the particle under motion. You could find that research work at the DOI given below. This work is available online, for your kind information.
Research Article Title: "Kinetic Energy of a Particle Independent of its Mass & Velocity"; DOI:10.9790/4861-1501013441
So, I request you to kindly update this novel equation and derivation on Wikipedia for the benefit of the wide readers of Wikipedia.
Thank you
PS: I am suggesting the following edits for addition [from START to END, present below] into the "Momentum" Page of Wikipedia; you could add more if you wish. Related novel equation for kinetic energy is also discovered in that research work at the above DOI document. You could update it as well on the Kinetic energy page of Wikipedia.
---START of EDIT---
Novel equation for "Momentum" recently discovered by research and reported in the scientific literature is given below. This discovery was done by the Indian researcher Mr. Bhargava R. Kotur, as recorded in the above DOI document.
p = sqrt (h. n . m)
In the above equation, p - stands for the Momentum, f - is the frequency of the body or particle under motion, m - is the mass of the body, and h - is the famous Planck's constant, sqrt - stands for the mathematical function "square root";
The derivation of the above work could be found at the DOI already mentioned earlier.
--- END of EDIT --- Ganesh Siva75 ( talk) 19:28, 10 February 2023 (UTC)