Momentum, Work and Energy Michael Fowler, U. Va.
PhysicsIn 530 A.D JohnPhiloponus in his commentary toAristotle’s physics developed a concept of momentum. Aristotle used the exampleof a thrown ball must be kept moving by something which was the motion of theair had claimed that everything that is moving must be kept moving by somethingAristotle’s theory was accepted until the time of Galileo,but a few were skeptical.Philoponus pointed out that it was difficult to believe Aristotle’sclaim that motion of an object is promoted by the same air that is resistingits passage.He proposed instead that a force was imparted to the objectin the act of throwing it.
Ibn Sina published his own theory of motion in The Book ofHealing in 1020 by Ibn Sina he published his own theory of motion. He agreedthat a force transmits to the object by the thrower – but unlike Philoponus,who believed that it was temporary, and would decline even in a vacuum –but itwas viewed differently by Ibn Sina who viewed it as a persistent. He understoodthat it required external forces such as air resistance to dissipate it.The European philosophers Peter Olivi and Jean Buridanrefined these ideas.
in about 1350 Buridan was made rector of the University ofParis, referred to momentum as proportional to the weight times the speed.Like Ibn S?n?, Buridan held that momentum would not go awayby itself; it could only dissipate if it encountered air resistance, friction,etc. René Descartes believed that the total “quantity of motion”in the universe is conserved: quantity of motion = size and speed. But thisequation is not specific because Descartes didn’t distinguish between mass andvolume.Leibniz, in his “Discourse on Metaphysics”, gave anexperimental argument against Descartes’ idea of “quantity of motion”.Leibniz dropped blocks of different sizes, differentdistances.He found that size x speed did not yield a conservedquantity.The first correct statement of conservation of momentum:English mathematician John Wallis, 1670Mechanica sive De Motu, Tractatus Geometricus:Isaac Newton’s Philosophiæ Naturalis Principia Mathematica,1687Defined “quantity of motion”, as “arising from the velocityand quantity of matter conjointly”-> mass x velocity – which identifies it as momentum.