Editing Free fall (section)

==History==
{{Main|History of gravitational theory}}

In the Western world prior to the 16th century, it was generally assumed that the speed of a falling body would be proportional to its weight—that is, a 10&nbsp;kg object was expected to fall ten times faster than an otherwise identical 1&nbsp;kg object through the same medium. The ancient Greek philosopher [[Aristotle]] (384–322 BC) discussed falling objects in ''[[Physics (Aristotle)|Physics]]'' (Book VII), one of the oldest books on [[mechanics]] (see [[Aristotelian physics]]). Although, in the 6th century, [[John Philoponus]] challenged this argument and said that, by observation, two balls of very different weights will fall at nearly the same speed.<ref>{{cite book|editor-first1=Morris R. |editor-last1=Cohen |editor-first2=I. E. |editor-last2=Drabkin |year=1958 |title=A Source Book in Greek Science |page=220 |location=Cambridge, MA |publisher=Harvard University Press}}</ref>

In 12th-century Iraq, [[Abu'l-Barakāt al-Baghdādī]] gave an explanation for the [[gravitational acceleration]] of falling bodies. According to [[Shlomo Pines]], al-Baghdādī's theory of motion was "the oldest negation of Aristotle's fundamental dynamic law [namely, that a constant force produces a uniform motion], [and is thus an] anticipation in a vague fashion of the fundamental law of [[classical mechanics]] [namely, that a force applied continuously produces acceleration]."<ref>{{cite encyclopedia  | last = Pines  | first = Shlomo  | title = Abu'l-Barakāt al-Baghdādī , Hibat Allah  | encyclopedia = [[Dictionary of Scientific Biography]]  | volume = 1  | pages = 26–28   | publisher = Charles Scribner's Sons  | location = New York  | year = 1970  | isbn = 0-684-10114-9 }} <br> ([[cf.]] Abel B. Franco (October 2003). "Avempace, Projectile Motion, and Impetus Theory", ''Journal of the History of Ideas'' '''64''' (4), pp. 521–546 [528].)</ref>

=== Galileo Galilei ===
{{See also|Galileo Galilei#Falling bodies}}{{See also|Galileo's Leaning Tower of Pisa experiment}}
According to a tale that may be apocryphal, in 1589–1592 Galileo [[Galileo's Leaning Tower of Pisa experiment|dropped two objects of unequal mass from the Leaning Tower of Pisa]]. Given the speed at which such a fall would occur, it is doubtful that Galileo could have extracted much information from this experiment. Most of his observations of falling bodies were really of bodies rolling down ramps. This slowed things down enough to the point where he was able to measure the time intervals with [[water clock]]s and his own pulse (stopwatches having not yet been invented). He repeated this "a full hundred times" until he had achieved "an accuracy such that the deviation between two observations never exceeded one-tenth of a pulse beat." In 1589–1592, Galileo wrote ''[[De Motu Antiquiora]]'', an unpublished manuscript on the motion of falling bodies.{{Citation needed|date=October 2019}}