MOTION AND SPEED

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MOTION AND SPEED

• DESCRIBING MOTION

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Motion

• Motion occurs when an object changes its
  position. Relative Motion Video
• Distance is how far an object moves.
• The SI unit of distance is the meter.
• Displacement is the distance and direction of an
  objects change in position from the starting
  point.

3
Speed

• Speed is the distance an object travels per unit
  of time.
• Any change over time is called a rate.
• Speed distance / time.
• Speed is a rate.

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Speed

• An object that covers equal distances in equal
  times is moving with constant speed.
• Average speed is the total distance traveled
  divided by the total time of travel.
• Instantaneous speed is the speed at a given point
  in time.

5
Velocity

• Velocity is the speed of an object AND its
  direction.
• Because velocity depends on direction as well as
  speed, the velocity of an object can change even
  if the speed remains constant.

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CHECK YOUR NEIGHBOR

• Is a drag racer interested in his speed or
  velocity?
• How about an airplane pilot?

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Distance vs. Time Graphs

• A distance vs time graph makes it possible to
  display the motion of an object over a period of
  time.
• The slope of a distance-time graph gives the
  velocity of the object in motion.
• The steeper the slope, the faster the object is
  moving.
• Constant Speed Positive Acceleration

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Distance vs. Time Graphs

• A straight line represents constant speed.
• A flat line represents 0 velocity no motion.
• A line returning to the baseline shows negative
  displacement. In other words, they returned to
  the start line.

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Accuracy vs. Precision

• Precision is the degree of exactness of a
  measurement.
• Accuracy is the extent to which a measurement
  approaches the true value.