Editing Momentum (section)

=== Impetus ===
{{Main|Theory of impetus}}

==== John Philoponus ====
In about 530 AD, [[John Philoponus]] developed a concept of momentum in ''On Physics'', a commentary to [[Aristotle]]'s ''[[Physics (Aristotle)|Physics]]''. Aristotle claimed that everything that is moving must be kept moving by something. For example, a thrown ball must be kept moving by motions of the air. Philoponus pointed out the absurdity in Aristotle's claim that motion of an object is promoted by the same air that is resisting its passage. He proposed instead that an impetus was imparted to the object in the act of throwing it.<ref>{{cite encyclopedia |title=John Philoponus |encyclopedia=Stanford Encyclopedia of Philosophy |url=http://plato.stanford.edu/entries/philoponus/#2.1 |access-date=26 July 2012 |date=8 June 2007}}</ref>

==== Ibn Sīnā ====
[[File:1950 "Avicenna" stamp of Iran (cropped).jpg|alt=Engraving of Ibn Sīnā|thumb|195x195px|Ibn Sīnā<br/>(980–1037)]]
In 1020, [[Avicenna|Ibn Sīnā]] (also known by his [[Latinisation of names|Latinized]] name Avicenna) read Philoponus and published his own theory of motion in ''[[The Book of Healing]]''. He agreed that an impetus is imparted to a projectile by the thrower; but unlike Philoponus, who believed that it was a temporary virtue that would decline even in a vacuum, he viewed it as a persistent, requiring external forces such as [[air resistance]] to dissipate it.<ref name="Espinoza">{{cite journal |last1=Espinoza |first1=Fernando |date=2005 |title=An analysis of the historical development of ideas about motion and its implications for teaching |journal=Physics Education |volume=40 |issue=2 |page=141 |bibcode=2005PhyEd..40..139E |doi=10.1088/0031-9120/40/2/002 |s2cid=250809354}}</ref><ref name="Nasr">{{Cite book |last1=Nasr |first1=Seyyed Hossein |title=The Islamic intellectual tradition in Persia |last2=Razavi |first2=Mehdi Amin |date=1996 |publisher=[[Routledge]] |isbn=978-0-7007-0314-2 |page=72 |author1-link=Seyyed Hossein Nasr}}</ref><ref name="Sayili">{{cite journal |author=[[Aydin Sayili]] |date=1987 |title=Ibn Sīnā and Buridan on the Motion of the Projectile |journal=Annals of the New York Academy of Sciences |volume=500 |issue=1 |pages=477–482 |bibcode=1987NYASA.500..477S |doi=10.1111/j.1749-6632.1987.tb37219.x |s2cid=84784804}}</ref>

==== Peter Olivi, Jean Buridan ====
In the 13th and 14th century, [[Peter Olivi]] and [[Jean Buridan]] read and refined the work of Philoponus, and possibly that of Ibn Sīnā.<ref name="Sayili" /> Buridan, who in about 1350 was made rector of the University of Paris, referred to [[Theory of impetus|impetus]] being proportional to the weight times the speed. Moreover, Buridan's theory was different from his predecessor's in that he did not consider impetus to be self-dissipating, asserting that a body would be arrested by the forces of air resistance and gravity which might be opposing its impetus.<ref>{{cite encyclopedia |title=Buridian, John |encyclopedia=Medieval Science, Technology and Medicine:an Encyclopedia |page=107 |last2=Livesay |first2=S. J. |last3=Wallis |first3=F. |first1=T. F. |last1=Glick}}</ref><ref name="Park">{{cite book |last=Park |first=David |url=https://archive.org/details/howwhyessayonori0000park |title=The how and the why: an essay on the origins and development of physical theory |date=1990 |publisher=Princeton University Press |others=With drawings by Robin Brickman |isbn=978-0-691-02508-7 |edition=3rd print |location=Princeton, New Jersey |pages=[https://archive.org/details/howwhyessayonori0000park/page/139 139–141] |url-access=registration}}</ref>