W3

• Aristotelian Conception


  • Vertical Motion: Natural motion, object will move and return to natural state based on composition (earth, water, air, fire)
  • Horizontal Motion: Violent motion, requires push/pull to maintain, stops when force removed
  • Projectile Motion: Parallel to ground until falls back, impetus kept until force forgotten
• Galilean Conception


  • Vertical Motion: In absence of resistance, objects fall at same rate regardless of weight, can reach uniform motion
  • Horizontal Motion: Unimpeded, object in motion continues in motion, no external force needed
  • Projectile Motion: Combination of uniform horizontal and uniformly accelerated vertical motion, continues without applied force
• Feather vs ball in vacuum

  Fall at same rate
• Air resistance slows down falling objects
• Gravity on Earth's surface is 9.8m/s^2
• With no air resistance, objects dropped simultaneously reach ground at same time regardless of mass
• Kicked ball is an example of projectile motion, not natural motion
• To Galileo, natural motion is largely vertical motion
• Between Aristotle and Galileo


  Whose view is more acceptable? Why?