Acceleration

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					                       Motion
• Position—separation of an object from a fixed
  reference point. Is a vector measurement.
  – += to the right or up
  – - = to the left or down
• Distance—requires no reference point. Is a
  scalar measurement.
• Instantaneous position
• Displacement—change in position. Symbolized
  as delta d.
                 Motion
• Motion diagrams—A series of images of a
  moving object that records its position
  after equal time intervals.
  – At rest
  – Speeding up
  – Slowing down
  – Constant speed
• Link to Motion Diagram Applet
• Link to Another Motion Diagram Site
    The Particle Model
• Replace an object with a single point at
  the center of the body.
  – You can use this model effectively if:
     • The size of the object is much less than the
       distance it moves.
     • Internal motions can be ignored.
         Coordinate System
• What is your frame of reference?
• Where is zero?
  – Origin—zero point.
  – You need to keep horizontal and vertical
    displacements on separate axes.
  – Position/displacement vectors on a motion
    diagram.
  – Can there be a negative position? Can there
    be a negative time?
             Velocity

• Average velocity=displacement/time
  – + = to the right or up
  – - = to the left or down
• Velocity vs. Speed
• Position-time graph
  – Slope=average velocity
  – Instantaneous velocity=slope of the
    tangent line to the point in question.
Position Time Graph
             Acceleration
• a=change in velocity over change in time
• Units
• Positive or negative—What do these signs
  mean?
• Deceleration
• Average Acceleration
                     Acceleration
• Velocity vs. Time graph
    – Slope=average acceleration
    – Slope of the tangent line to the graph=instantaneous
      acceleration.
    – Area under the curve=the total displacement.
    – Velocity/Time Graph Applet
    – Velocity/Time, Position/Time, and Acceleration/Time graph
      applets
•   Instantaneous Acceleration
•   Uniform or Constant Acceleration
•   Link to PHET Moving Man Simulation
•   Equations
•   Acceleration due to gravity
Velocity Time Graph
     Acceleration Due to Gravity
•   Lowercase g
•   -9.8 meters per second squared
•   -32 feet per second squared
•   Sample Problems
         Acceleration Equations
•   vf=vI + at
•   Vf2=vi2 + 2ad
•   d=vit +1/2 at2
•   d=1/2(vf + vi)t

				
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posted:5/3/2013
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