Talk:Kinetic energy

Semi-protected edit request on 8 July 2025

change "The principle of classical mechanics that E ∝ mv² is conserved was first developed by Gottfried Leibniz and Johann Bernoulli, who described kinetic energy as the living force or vis viva." to "The principle of classical mechanics that E ∝ mv² is conserved was first noticed by Christiaan Huygens. Later, Gottfried Leibniz and Johann Bernoulli described kinetic energy as the living force or vis viva." Huruntz (talk) 16:16, 8 July 2025 (UTC)

References

 Not done: I couldn't find a quote that directly supports this, nor in this:

Joella G. Yoder (1988). Unrolling Time: Christiaan Huygens and the Mathematization of Nature (illustrated, reprinted ed.). Cambridge University Press. p. 0. ISBN 978-0-521-34140-0..

How exactly does your source support this? - DVdm (talk) 18:30, 8 July 2025 (UTC)

The Feather source cited in the article is not correctly summarized. Neither the current content not the requested edit is consistent with the source. The development of the concept was nuanced, "first" makes no sense. I linked the internet archive text. I will try to work on a better summary if someone does not get to it first. Johnjbarton (talk) 22:31, 8 July 2025 (UTC)

Blackwell's text is a translation of Huygens' work, made ten years before Leibniz. See Proposition 11 in this text: "If two bodies collide with each other, and if the ratio of both their magnitudes and their speeds is given either in numbers or in lines, then the sum of their magnitudes multiplied by the squares of their respective velocities is equal before and after the collision." What is at stake here, if not the conservation of kinetic energy? See also the translator's footnote on the same page. Huruntz (talk) 01:32, 9 July 2025 (UTC)

And here is ChatGPT's answer: https://chatgpt.com/s/t_686dc7dd05108191b84e10f1cb365727 Huruntz (talk) 01:39, 9 July 2025 (UTC)

Moreover, the wiki page on the law of conservation of energy already mentions Huygens' work: "In 1669, Christiaan Huygens published a brief account on his laws of collision. Among the quantities he listed as being invariant before and after the collision of bodies were both the sum of their linear momenta as well as the sum of their kinetic energies. However, the difference between elastic and inelastic collision was not understood at the time. This led to the dispute among later researchers as to which of these conserved quantities was the more fundamental. In his Horologium Oscillatorium, Huygens gave a much clearer statement regarding the height of ascent of a moving body, and connected this idea with the impossibility of perpetual motion. His study of the dynamics of pendulum motion was based on a single principle, known as Torricelli's Principle: that the center of gravity of a heavy object, or collection of objects, cannot lift itself. Using this principle, Huygens was able to derive the formula for the center of oscillation by an "energy" method, without dealing with forces or torques." Huruntz (talk) 01:46, 9 July 2025 (UTC)

I do not insist on the version I have proposed in the form in which I have composed it. True, it turned out to be somewhat awkward. However, in this case, giving priority to Leibniz over Hugens would be completely unfair and historically incorrect. Huruntz (talk) 01:59, 9 July 2025 (UTC)

Was Leibniz familiar with Huygens' work? See https://chatgpt.com/s/t_686dd39dca788191969ea064669f730c Huruntz (talk) 02:29, 9 July 2025 (UTC)

Nothing from ChatGPT or any other AI is suitable for Wikipedia. That content only sounds good, but the sources it gives are almost 100% fabricated. See Wikipedia:Large language models. Ask it for sources and see for yourself. Every addition to wikipedia must be verifiable to reliable sources. That is all that matters. If you don't have sources to verify content, and have not verified them yourself, please do not post here. Johnjbarton (talk) 03:34, 9 July 2025 (UTC)

My source is Huygens himself, translated into English by Blackwall, who speaks for himself. The ChatGPT link is included here in passing. Huruntz (talk) 06:52, 9 July 2025 (UTC)

Here is a link to "Opera reliqua" by Huygens. Page 793 gives the Proposition 11 I refer to in the original Latin text : https://archive.org/details/operareliqua00huyg/page/n792/mode/1up Huruntz (talk) 07:54, 9 July 2025 (UTC)

Please see this discussion of primary, secondary and tertiary sources. We should not assume the terminology Huygens used matches modern usage. In general all claims of "first" should be sourced to secondary sources by historians on the topic.

The conservation of energy article is not well sources either but it supports my claim that the story here is complicated. Johnjbarton (talk) 16:06, 9 July 2025 (UTC)

I contest the claim that "the story here is complicated". In this context, I recommend examining the article authored by George E. Smith titled "The vis viva dispute: A controversy at the dawn of dynamics (2006)" (https://doi.org/10.1063/1.2387086). This article elaborates extensively on Huygens' contributions. Notably, at the time this article was published, George E. Smith held the position of Professor of Philosophy at Tufts University in Medford, Massachusetts, and served as the Acting Director of the Dibner Institute for the History of Science and Technology at MIT in Cambridge. He also cites Lagrange, stating: "Lagrange attributed the principle of the conservation of vis viva to Huygens alone, with no mention of Leibniz, citing Huygens’s solution for the center of oscillation rather than his earlier solution of the impact problem." Regardless, if, after reviewing George E. Smith's article, you still harbor uncertainties regarding Huygens's unequivocal priority, I will not attempt to change your perspective. Huruntz (talk) 19:03, 9 July 2025 (UTC)

Thanks for the excellent George Smith source. It confirms my assertions above concerning the complicated story. The entire source is about these complications. At the beginning we read:

• "The most celebrated of those disputes, concerning the conservation of vis viva (Latin for “living force” and akin to what we now call kinetic energy),..."

which is to say that the unequivocal priority is for vis viva, "akin" to the article topic.

I agree that the current content does not adequately represent reliable sources and needs work. The sources you have given will help. Johnjbarton (talk) 03:52, 10 July 2025 (UTC)

Let me express the hope that in the forthcoming edition of the section under discussion Huygens' seminal contribution will receive the recognition it rightfully merits. 2A00:F3C:E0FA:0:AD05:4544:94CB:8B8D (talk) 18:32, 10 July 2025 (UTC)

Consistent notation

The section called "Low Speed limit" uses "m" whereas the section above it ("Relativistic Kinetic Energy") uses "m__0". It would be good to be consistent and always use "m_0" for rest mass. — Preceding unsigned comment added by 2600:1702:5EB5:250:2B7C:439C:8488:C2C (talk) 23:40, 20 July 2025 (UTC)

Thanks. I removed the _0 for rest mass. This old notation is not used in modern physics. Mass is always rest mass and often given in units of energy anyway. It would be nice to have a paragraph on the _0 notation if we could find a source that discusses it explicitly. Johnjbarton (talk) 15:08, 21 July 2025 (UTC)

Semi-protected edit request on 10 January 2026

The current text confusingly assumes units are such that c = 1. Then it later switches to using c in equations. It also fails to include the formula $E_{K}=mc^{2}(\gamma -1)$, which is the standard form.

Change text:

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==Relativistic kinetic energy == <div role="note" class="hatnote navigation-not-searchable">See also: [[:Mass in special relativity]] and [[:Tests of relativistic energy and momentum]]</div> If a body's speed relative to an inertial frame is a significant fraction of the [[speed of light]], it is necessary to use relativistic mechanics to calculate its kinetic energy relative to that frame. In relativistic mechanics, energy combines with momentum in a way analogous to the combination of time and space into [[spacetime]]. The energy component in the inertial frame can be expressed as:<sup class="reference nowrap"><span title="Page / location: 195">:&hairsp;195&hairsp;</span></sup> where and is the object's [[invariant mass|(rest) mass]], speed, and ''c'' the speed of light in vacuum. If the body is at rest in the inertial frame, and , so .<sup class="reference nowrap"><span title="Page / location: 201">:&hairsp;201&hairsp;</span></sup> The rest energy of an object is its rest mass in units where . In [[International_System_of_Units|SI]] units, . The kinetic energy can then be defined as the total energy minus the rest energy:<sup class="reference nowrap"><span title="Page / location: 201">:&hairsp;201&hairsp;</span></sup>

+

==Relativistic kinetic energy == <div role="note" class="hatnote navigation-not-searchable">See also: [[:Mass in special relativity]] and [[:Tests of relativistic energy and momentum]]</div> If a body's speed relative to an inertial frame is a significant fraction of the [[speed of light]], it is necessary to use relativistic mechanics to calculate its kinetic energy relative to that frame. In relativistic mechanics, energy combines with momentum in a way analogous to the combination of time and space into [[spacetime]]. The energy component in the inertial frame can be expressed as:<sup class="reference nowrap"><span title="Page / location: 195">:&hairsp;195&hairsp;</span></sup> where and is the object's [[invariant mass|(rest) mass]], speed, and ''c'' the speed of light in vacuum. If the body is at rest in the inertial frame, and , so .<sup class="reference nowrap"><span title="Page / location: 201">:&hairsp;201&hairsp;</span></sup> The kinetic energy can then be defined as the total energy minus the rest energy:<sup class="reference nowrap"><span title="Page / location: 201">:&hairsp;201&hairsp;</span></sup>

Dalekoepp (talk) 18:00, 10 January 2026 (UTC)

 Not done: It's not clear what changes you want made, as the old text highlighted in orange doesn't exist in the article. Please detail the specific changes in a "change X to Y" format and open a new edit request. MosquitoDestroyer (talk | mosquitoes destroyed) 20:33, 11 January 2026 (UTC)