Editing Friction (section)

==History==
Many ancient authors including [[Aristotle]], [[Vitruvius]], and [[Pliny the Elder]], were interested in the cause and mitigation of friction.<ref name="Chatterjee-2008">{{cite thesis |last=Chatterjee |first=Sudipta |year=2008 |title=Tribological Properties of Pseudo-elastic Nickel-titanium |publisher=University of California |via=ProQuest |isbn=978-0-549-84437-2 |pages=11–12 |url=https://books.google.com/books?id=rX6xfoEaYtQC&pg=PA12 |quote=Classical Greek philosophers like Aristotle, Pliny the Elder and Vitruvius wrote about the existence of friction, the effect of lubricants and the advantages of metal bearings around 350 B.C. }}{{Dead link|date=May 2024 |bot=InternetArchiveBot |fix-attempted=yes }}</ref> They were aware of differences between static and kinetic friction with [[Themistius]] stating in 350 {{Smallcaps2|A.D.}} that "it is easier to further the motion of a moving body than to move a body at rest".<ref name="Chatterjee-2008"/><ref>{{cite book |last1=Fishbane |first1=Paul M. |last2=Gasiorowicz |first2=Stephen |last3=Thornton |first3=Stephen T. |year=1993 |title=Physics for Scientists and Engineers |edition=Extended |volume=I |publisher=Prentice Hall |location=Englewood Cliffs, New Jersey |isbn=978-0-13-663246-7 |page=135 |quote=Themistius first stated around 350 {{Smallcaps2|{{sic|B.C.|expected=A.D.}}}} that kinetic friction is weaker than the maximum value of static friction.}}</ref><ref>{{cite book |last=Hecht |first=Eugene |date=2003 |title=Physics: Algebra/Trig |edition=3rd |publisher=Cengage Learning |isbn=978-0-534-37729-8}}</ref><ref>{{cite book |last=Sambursky |first=Samuel |date=2014 |title=The Physical World of Late Antiquity |publisher=Princeton University Press |isbn=978-1-4008-5898-9 |pages=65–66 |url=https://books.google.com/books?id=Yvz_AwAAQBAJ&pg=PA65 |access-date=2016-11-01 |archive-date=2024-10-07 |archive-url=https://web.archive.org/web/20241007091047/https://books.google.com/books?id=Yvz_AwAAQBAJ&pg=PA65#v=onepage&q&f=false |url-status=live }}</ref>

The classic laws of sliding friction were discovered by [[Leonardo da Vinci]]  in 1493, a pioneer in [[tribology]], but the laws documented in his notebooks were not published and remained unknown.<ref name="Dowson-1997" >{{cite book |last=Dowson |first=Duncan |year=1997 |title=History of Tribology |edition=2nd |publisher=Professional Engineering Publishing |isbn=978-1-86058-070-3}}</ref><ref name="Armstrong-Hélouvry-1991" >{{cite book |last=Armstrong-Hélouvry |first=Brian |year=1991 |title=Control of machines with friction |publisher=Springer |location=USA |page=10 |url=https://books.google.com/books?id=0zk_zI3xACgC&pg=PA10 |isbn=978-0-7923-9133-3 |access-date=2020-06-07 |archive-date=2024-10-07 |archive-url=https://web.archive.org/web/20241007090932/https://books.google.com/books?id=0zk_zI3xACgC&pg=PA10#v=onepage&q&f=false |url-status=live }}</ref><ref name="van Beek">{{cite web |last=van Beek |first=Anton |title=History of Science Friction |publisher=tribology-abc.com |url=http://www.tribology-abc.com/abc/history.htm |access-date=2011-03-24 |archive-date=2011-08-07 |archive-url=https://web.archive.org/web/20110807185735/http://www.tribology-abc.com/abc/history.htm |url-status=live }}</ref><ref>{{cite journal |last=Hutchings |first=Ian M.  |date=2016 |title=Leonardo da Vinci's studies of friction |journal=Wear  |volume=360–361  |pages=51–66  |doi=10.1016/j.wear.2016.04.019 |url=http://www.ifm.eng.cam.ac.uk/uploads/Hutchings_Leonardo_Friction_2016_v2.pdf |archive-url=https://web.archive.org/web/20160803211351/http://www.ifm.eng.cam.ac.uk/uploads/Hutchings_Leonardo_Friction_2016_v2.pdf |archive-date=2016-08-03 |url-status=live }}</ref><ref>{{cite journal |last=Hutchings |first=Ian M. |date=2016-08-15 |title=Leonardo da Vinci's studies of friction |journal=Wear |doi=10.1016/j.wear.2016.04.019 |volume=360–361 |pages=51–66 |url=https://www.repository.cam.ac.uk/handle/1810/255781 |access-date=2019-07-09 |archive-date=2021-09-18 |archive-url=https://web.archive.org/web/20210918100744/https://www.repository.cam.ac.uk/handle/1810/255781 |url-status=live }}</ref><ref>{{cite web |last=Kirk |first=Tom |date=July 22, 2016 |title=Study reveals Leonardo da Vinci's 'irrelevant' scribbles mark the spot where he first recorded the laws of friction |website=phys.org |url=http://phys.org/news/2016-07-reveals-leonardo-da-vinci-irrelevant.html |access-date=2016-07-26 |archive-date=2016-07-25 |archive-url=https://web.archive.org/web/20160725081116/http://phys.org/news/2016-07-reveals-leonardo-da-vinci-irrelevant.html |url-status=live }}</ref> These laws were rediscovered by [[Guillaume Amontons]] in 1699<ref name="Popova-2015">{{Cite journal|last1=Popova|first1=Elena|last2=Popov|first2=Valentin L.|date=2015-06-01|title=The research works of Coulomb and Amontons and generalized laws of friction|journal=Friction|language=en|volume=3|issue=2|pages=183–190|doi=10.1007/s40544-015-0074-6|doi-access=free}}</ref> and became known as Amonton's three laws of dry friction.   Amontons presented the nature of friction in terms of surface irregularities and the force required to raise the weight pressing the surfaces together. This view was further elaborated by [[Bernard Forest de Bélidor]]<ref>[[Bernard Forest de Bélidor|Forest de Bélidor, Bernard]]. "[http://gallica.bnf.fr/ark:/12148/btv1b53032692q.r=Belidor%2C%20Bernard%20Forest%20de Richtige Grund-Sätze der Friction-Berechnung] {{Webarchive|url=https://web.archive.org/web/20210427035523/http://gallica.bnf.fr/ark:/12148/btv1b53032692q.r=Belidor%2C%20Bernard%20Forest%20de |date=2021-04-27 }}" ("Correct Basics of Friction Calculation"), 1737, (in [[German language|German]])</ref> and [[Leonhard Euler]] (1750), who derived the [[angle of repose]] of a weight on an inclined plane and first distinguished between static and kinetic friction.<ref>{{cite web
  | title = Leonhard Euler
  | work = Friction Module
  | publisher = Nano World
  | year = 2002
  | url = http://www.nano-world.org/frictionmodule/content/0200makroreibung/0400historisch/0300euler/?lang=en
  | access-date = 2011-03-25
  | archive-url = https://web.archive.org/web/20110507032615/http://www.nano-world.org/frictionmodule/content/0200makroreibung/0400historisch/0300euler/?lang=en
  | archive-date = 2011-05-07

  }}</ref>
[[John Theophilus Desaguliers]] (1734) first recognized the role of [[adhesion]] in friction.<ref name="Goedecke-2014">{{cite book
 | last1  = Goedecke
 | first1  = Andreas
 | title  = Transient Effects in Friction: Fractal Asperity Creep
 | publisher  = Springer Science and Business Media
 | date  = 2014
 | page  = 3
 | url  = https://books.google.com/books?id=kP7EBAAAQBAJ&q=Theophilus+Desaguliers&pg=PA3
 | isbn  = 978-3-7091-1506-0
 | access-date  = 2020-11-11
 | archive-date  = 2024-10-07
 | archive-url  = https://web.archive.org/web/20241007091005/https://books.google.com/books?id=kP7EBAAAQBAJ&q=Theophilus+Desaguliers&pg=PA3#v=snippet&q=Theophilus%20Desaguliers&f=false
 | url-status  = live
 }}</ref> Microscopic forces cause surfaces to stick together; he proposed that friction was the force necessary to tear the adhering surfaces apart.

The understanding of friction was further developed by [[Charles-Augustin de Coulomb]] (1785).<ref name="Popova-2015"/> Coulomb investigated the influence of four main factors on friction: the nature of the materials in contact and their surface coatings; the extent of the surface area; the normal pressure (or load); and the length of time that the surfaces remained in contact (time of repose).<ref name="Dowson-1997" /> Coulomb further considered the influence of sliding velocity, temperature and humidity, in order to decide between the different explanations on the nature of friction that had been proposed. The distinction between static and dynamic friction is made in Coulomb's friction law (see below), although this distinction was already drawn by [[Johann Andreas von Segner]] in 1758.<ref name="Dowson-1997" />
The effect of the time of repose was explained by [[Pieter van Musschenbroek]] (1762) by considering the surfaces of fibrous materials, with fibers meshing together, which takes a finite time in which the friction increases.

[[John Leslie (physicist)|John Leslie]] (1766–1832) noted a weakness in the views of Amontons and Coulomb: If friction arises from a weight being drawn up the inclined plane of successive [[asperities]], then why is it not balanced through descending the opposite slope? Leslie was equally skeptical about the role of adhesion proposed by Desaguliers, which should on the whole have the same tendency to accelerate as to retard the motion.<ref name="Dowson-1997" /> In Leslie's view, friction should be seen as a time-dependent process of flattening, pressing down asperities, which creates new obstacles in what were cavities before.

[[File:Heat by friction.webm|thumb|Heat by friction captured by a thermal camera]]
In the long course of the development of the [[law of conservation of energy]] and of the [[first law of thermodynamics]], friction was recognised as a mode of conversion of [[mechanical work]] into [[heat]]. In 1798, [[Benjamin Thompson]] reported on cannon boring experiments.<ref>[[Benjamin Thompson]] (1798). [https://books.google.com/books?id=6lBFAAAAcAAJ&pg=PA80 "An inquiry concerning the source of the heat which is excited by friction,"] {{Webarchive|url=https://web.archive.org/web/20241007090951/https://books.google.com/books?id=6lBFAAAAcAAJ&pg=PA80#v=onepage&q&f=false |date=2024-10-07 }} ''Philosophical Transactions of the Royal Society of London'', '''88''' :   80–102. {{doi|10.1098/rstl.1798.0006}}</ref>

[[Arthur Jules Morin]] (1833) developed the concept of sliding versus rolling friction.

In 1842, [[Julius Robert Mayer]] frictionally generated heat in paper pulp and measured the temperature rise.<ref>Blundell, S.J., Blundell, K.M. (2006). ''Concepts in Thermal Physics'', Oxford University Press, Oxford UK, {{ISBN|978-0-19-856769-1}}, p. 106.</ref> In 1845, Joule published a paper entitled ''The Mechanical Equivalent of Heat'', in which he specified a numerical value for the amount of mechanical work required to "produce a unit of heat", based on the friction of an electric current passing through a resistor, and on the friction of a paddle wheel rotating in a vat of water.<ref>[[James Prescott Joule|Joule, J.P.]] (1845).{{cite journal|last=Joule|first=J. P.|title=On the Mechanical Equivalent of Heat|journal=Philosophical Transactions of the Royal Society of London|date=1850|volume=140|pages=61–82|doi=10.1098/rstl.1850.0004|url=https://archive.org/stream/philtrans00608634/00608634#page/n0/mode/2up|display-authors=0|doi-access=free}}
</ref>

[[Osborne Reynolds]] (1866) derived the equation of viscous flow.  This completed the classic empirical model of friction (static, kinetic, and fluid) commonly used today in engineering.<ref name="Armstrong-Hélouvry-1991" /> In 1877,  [[Fleeming Jenkin]] and [[James Alfred Ewing|J. A. Ewing]] investigated the continuity between static and kinetic friction.<ref>[[Fleeming Jenkin]] & [[James Alfred Ewing]] (1877) "[https://www.biodiversitylibrary.org/item/121556#page/322/mode/1up On Friction between Surfaces moving at Low Speeds] {{Webarchive|url=https://web.archive.org/web/20210918100735/https://www.biodiversitylibrary.org/item/121556#page/322/mode/1up |date=2021-09-18 }}", ''[[Philosophical Magazine]]'' Series 5, volume 4, pp 308–10; link from [[Biodiversity Heritage Library]]</ref>

In 1907, [[George H. Bryan|G.H. Bryan]] published an investigation of the foundations of thermodynamics, ''Thermodynamics: an Introductory Treatise dealing mainly with First Principles and their Direct Applications''. He noted that for a rough body driven over a rough surface, the mechanical work done by the driver exceeds the mechanical work received by the surface. The lost work is accounted for by heat generated by friction.<ref>{{cite book |last1=Bryan |first1=George Hartley |title=Thermodynamics, an introductory treatise dealing mainly with first principles and their direct applications |url=https://archive.org/stream/thermodynamicsin00bryauoft/thermodynamicsin00bryauoft_djvu.txt |publisher=Leipzig, Teubner |pages=48–49 |date=1907 |access-date=23 June 2023}}</ref>

Over the years, for example in his 1879 thesis, but particularly in 1926, [[Planck]] advocated regarding the generation of heat by rubbing as the most specific way to define heat, and the prime example of an irreversible thermodynamic process.<ref name="Planck 1926">[[Max Planck|Planck, M.]] (1926). "Über die Begründung des zweiten Hauptsatzes der Thermodynamik", ''Sitzungsber. Preuss. Akad. Wiss., Phys. Math. Kl.'', 453—463.</ref>

The focus of research during the 20th century has been to understand the physical mechanisms behind friction. [[Frank Philip Bowden]] and [[David Tabor (physicist)|David Tabor]] (1950) showed that, at a [[Microscopic scale|microscopic level]], the actual area of contact between surfaces is a very small fraction of the apparent area.<ref name="van Beek" />  This actual area of contact, caused by asperities increases with pressure. The development of the [[atomic force microscope]] (ca. 1986)  enabled scientists to study friction at the [[Atomic units|atomic scale]],<ref name="Armstrong-Hélouvry-1991" /> showing that, on that scale, dry friction is the product of the inter-surface [[shear stress]] and the contact area. These two discoveries explain Amonton's first law ''(below)''; the macroscopic proportionality between normal force and static frictional force between dry surfaces.