Aristotles Laws of Motion

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Aristotles Laws of Motion
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V a F
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V a F

• Velocity is zero whenever force is zero.

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V a w

• Heavier falls faster
• Plastic bag
• Pumpkin
• Does not mean light things go faster when you
  push on them.
• (I dont know how Aristotle dealt with that
  observation. That may have been another law which
  I am unaware of.)

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V a 1/?

• Density of the medium through which the object
  travels. (syrup, water, air, vacuum)
• Has nothing to do with the density of the object
  (floating vs sinking)

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Rocks Fall More Slowly in Water
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Underwater Chariot Racing is Slower
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Natural Motion and Violent Motion

• Nature is at peace when everything has no motion
  that is the natural state of an object. Motion
  is the result of an imbalance.
• Motion has a purpose (purpose in the cosmic
  sense of the word)
• Natural motion restores order and balance (Earth
  at center, then water, air, fire, and ether in
  the heavens).
• Violent motion fulfills the desire of the mover.

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Galileo to the Rescue!
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V a w intuitive, but wrong
Wood
Rock
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Already Know Weight Law is WrongWe see this
Density law could still be correct if we saw
this
Wood
Rock
Wood
Rock
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Of course, we know what really happens the
density of the objects has as much to do with
their motion as the density of the medium.
Wood
Rock
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• Galileo worked with ramps and rolling balls.
• He noticed

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V a F you didnt deal with friction correctly.

• Suppose there were no friction.

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• Galileo worked with ramps and rolling balls.
• He noticed objects move until friction slows them
  down.
• Forces make objects move.
• Forces make objects stop.
• Velocity is constant whenever force is zero.

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Aristotle
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Galileo