"John Philoponus (c. 490-570) of Alexandria... refuted Aristotle's theory that the velocities of falling bodies in a given medium are proportional to their weight, making the observation that "if one lets fall simultaneously from the same height two bodies differing greatly in weight, one will find that the ratio of the times of their motion does not correspond to the ratios of their weights, but the difference in time is a very small one." …He also criticized Aristotle's antiperistasis theory of projectile motion, which states that the air displaced by the object flows back to push it from behind. Instead Philoponus concluded that "some incorporeal kinetic power is imparted by the thrower to the object thrown" and that "if an arrow or a stone is projected by force in a void, the same will happen much more easily, nothing being necessary except the thrower." This is the famous "impetus theory," which was revived in medieval Islam and again in fourteenth century Europe, giving rise to the beginning of modern dynamics."
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People from New York CityTravel writersUniversity of Oxford alumniPhysicists from the United StatesHistorians of science
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John Freely
John Freely (26 June 1926 – 20 April 2017) was an American physicist, teacher, and author of popular travel and history books on Istanbul, Athens, Venice, Turkey, Greece, and the Ottoman Empire.
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