Chapter Two and Chapter Three

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Chapter Two and Chapter Three
2
Objectives

• What is Motion?
• Measuring Motion
• Artstotles views
• Horizontal versus Vertical Motion
• Newtons Laws of Motion
• Momentum
• Circular Motion
• Law of Gravition

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Motion and Measuring Motion

• Change in position
• Passage of time
• Measuring Motion
• Speed
• Distance/time
• Instantaneous versus Average
• Velocity
• Acceleration
• Change of velocity/ time
• Acceleration versus Deacceleration

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Motion Examples

• Speed Example 2.1
• Acceleration Example 2.3

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Aristotles Views

• Two spheres
• Sphere of perfection versus Sphere of change
• Natural versus Forced Motion
• Elements earth, air, fire, and water
• Reqired force by people
• Could not explain interaction at a distance

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Horizontal versus Vertical Motion

• Horizontal
• Leaning Tower of Pisa
• Rolling Balls
• Inertia
• Vertical
• Free fall
• Galileo versus Aristotle
• Constant versus Accelerating objects

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Horizontal versus Vertical (cont.)

• Vertical (cont.)
• D(1/2)at2
• Confirmed with rolling ball
• Ag9.8 m/s2
• T?(2d/g)
• Compound Motion
• A combination of vertical and horizontal motion

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Newtons Laws of Motion

• Edmund Halley
• Christmas Day, 1642
• Trinity College, Cambridge
• Halley Principia, planetary motion
• Well accepted

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Newtons First Law of Motion

• Every object retains it state of motion of its
  stat of uniform straight-line motion unless acted
  up by an unbalanced force
• Inertia
• Mass

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Newtons Second Law of Motion

• The acceleration of an object is directly
  proportional to the net force acting on it and
  inversely proportional to the mass of the object
• Weight is a force
• F ma

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Newtons Third Law of Motion

• Whenever two objects interact, the force exerted
  on one object is equal in size and opposite in
  direction to the force exerted on the other
  object
• Example Standing on the Floor
• FAB FBA

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Newton Examples

• Second Law Example 3.1
• Third Law Example 3.5

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Momentum

• The total momentum of a group of interacting
  objects remains the same in the absence of
  external forces
• Pmv
• Unusual
• P gives no clues
• Kg m/s has no other name

14
Circular Motion

• Centripetal versus Centrifugal
• No true Centrifugal
• All circular motion inside
• acv2/r
• Fmv2/r

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Newtons Laws of Gravitation

• Every object in the universe is attractedto
  every other object with a force that is directly
  proportional to the product of their masses
• F GM1M2/R2
• G 6.67 X 10-11 Nm2/kg2

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Force and Gravitation Examples

• Circular Motion Example 3.7
• Gaviation Example 3.9, 3.10

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Homework

• Chapter Two
• Questions for Thought
• 1, 6, 9
• Parallel Exercise
• 3, 5
• Chapter Three
• Questions for Thought
• 1, 4, 9
• Parallel Exercise
• 4, 10