Picturing Motion Dot Diagrams by vhd10964

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									    Picturing Motion: Dot Diagrams



• If you related the position of the runner to the background in each
  frame taken in 1 second intervals, you would conclude that the student
  is in motion.




• This series of images, taken at regular intervals, creates a motion
  diagram for the change in the student’s state of motion.
• Roll a ball along a horizontal
  surface, and its velocity is
  constant because no component
  of gravitational force acts
  horizontally
• Drop it, and it accelerates
  downward and covers greater
  vertical distances each second.
By noting the distance the object moves in
equal time intervals, you can determine the
          object’s state of motion
• A: at rest
• B: moving at a
  constant speed
• C: speeding up
• D: slowing down.
Use a dot motion diagram model to draw simplified
                motion diagrams

• A: at rest
• B: moving at a
  constant speed
• C: speeding up
• D: slowing down.
• Use the dot diagram model to draw a
  motion diagram for an object moving at a
  constant speed.

• Use the dot diagram model to draw a
  motion diagram for an object starting at
  rest and speeding up.

• Use the dot diagram model to draw a
  motion diagram for an object that starts
  from rest, speeds up to a constant speed,
  and then slows to a stop.
• Use the dot diagram model to draw a
  motion diagram for a wheel turning at a
  constant speed. First place the dot at the
  hub of the wheel. What would the diagram
  look like if the dot were placed on the rim
  of the wheel?
     Dot Diagrams & Vector Quantities
• To determine displacement, velocity, and
  acceleration, a coordinate system must be
  specified.
• Normally the positive values of x extend
  horizontally to the right, and the positive
  values of y extend vertically upward.
• The sign of the average velocity depends
  upon the chosen coordinate system. The
  coordinate systems in a and b are equally
  correct
• Color Conventions
  – Displacement vectors are green.
  – Velocity vectors are red.
  – Accelerations vectors are violet
  Graphs and motion diagrams are useful in
  differentiating constant motion and motion
               that is accelerated.
• A speed-versus-time graph
• A distance-versus-time graph
• The sign of the acceleration depends upon
  the chosen coordinate system.
• Ex: a ball being rolled up an inclined driveway
                                   +
Freefall
• The rate at which the velocity
  changes each second is the
  same whether the ball is going
  upward or downward.




                                   -
    Refer to the motion graph below to find
1.   The time interval(s) for positive acceleration
2.   The time interval(s) for negative acceleration
3.   The time interval(s) for constant velocity
4.   The time interval(s) for zero acceleration
5.   At what time(s) does the car appear to be at rest?
6.   At what time(s) does the car turn around and
     move in the opposite direction?

								
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