Dynamics: The Why of Motion

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Dynamics The Why of Motion

• Inertia, Force, and Newtons Laws

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Inertia

• The property of an object to persist in its
  current state of rest or uniform motion.
• Generally refer to frames of reference fixed on
  the earth (since earth rotates, technically the
  frame is accelerating)
• Two frames of reference- inertial and non
  inertial (or accelerating)

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Forces

• Any kind of push or pull e.g. pushing on a
  stroller, pulling on a rope, kicking a ball, etc
• Forces can act on an object and the result can be
  no net motion.
• An object either at rest or travelling at
  constant velocity is in equilibrium

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Forces

• Can be contact where there is physical contact
  between two objects e.g. shooting a basketball,
  pulling on the handle of a wagon
• Can be action-at a-distance forces which do not
  have physical contact e.g. the earth pulls on the
  moon, electrical charges attract or repel,
  magnets attract or repel

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Forces 4 Fundamental Types

• Strong Nuclear
• Weak Nuclear
• Electromagnetic
• Gravitational

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Newtons First Law Law of Inertia

• An object at rest will remain at rest and an
  object in motion will continue in motion with a
  constant velocity (i.e. in a straight line)
  unless it experiences a net external force

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Newtons Second Law Law of Acceleration

• The acceleration of an object is directly
  proportional to the resultant force acting on it
  (in the same direction) and is inversely
  proportional to the mass of the object

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Newtons Third Law Law of Interaction

• If two objects interact, then the force on object
  1 by object 2 is equal and opposite to the force
  exerted on object 2 by object 1
• F1 2 - F 2 1