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SUMMARY:Aristotle\, projectiles and guns - Stephen Walley\, SMF Group\, Th
 e Cavendish Laboratory
DTSTART:20171102T160000Z
DTEND:20171102T170000Z
UID:TALK82951@talks.cam.ac.uk
CONTACT:Stephen Walley
DESCRIPTION:When guns were developed in Europe in the 14th century\, the t
 heory of projectile motion was not the one we are familiar with today due 
 to Galileo and Newton but the one taught by Aristotle approximately 1700 y
 ears earlier. In addition to Aristotle's wide-ranging philosophical concer
 ns\, his theory arose from the observation in everyday life that if an obj
 ect is moving something must be moving it. This idea works very well for t
 he horse and cart but is puzzling if you apply it to a thrown stone or spe
 ar. Problems with Aristotle’s theory of projectile motion were identifie
 d by one or two people between his time and the 14th century\, particularl
 y John Philiponus (6th century AD) and John Buridan (14th century AD). An 
 archer or a spearman does not need a theory of projectile motion\, just a 
 great deal of practice. But once the gun was invented it became important 
 to know what angle a barrel should be oriented at and how much propellant 
 to use\, particularly as gunpowder was expensive. However\, for many years
  afterwards the manufacturing techniques used meant that cannonballs were 
 a loose fit to gun-barrels making cannons both inaccurate and of poor repr
 oducibility shot-to-shot. Also air resistance makes the trajectory both im
 possible to calculate and qualitatively similar to theories based on Arist
 otle’s writings. It was not until Galileo and Newton worked on the probl
 em that a better theory of ideal projectile motion was arrived at.
LOCATION:Mott Seminar Room\, Cavendish Laboratory
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