1 Dimensional Kinematics

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1 -Dimensional Kinematics

• Advanced Physics Honors
• Nerinx Hall

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What is 1-D Motion?

• Motion that you could describe as moving solely
  in one direction.
• Well describe 1-D motion as movement along the
  x-axis

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Features of 1-D Motion

• Distance traveled
• Direction traveled
• Time it took to travel that distance

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Distance vs. Displacement Whats the Difference?

• Distance is a scalar -- it is just a number
  representing solely the magnitude of travel.
• Displacement is a vector -- it tells you the
  change in position of the object by describing
  the magnitude and direction of travel.

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Assign Coordinate Axes to your Sketches

• Coordinates Axes defines your frame of reference
• Always include coordinate axes with your sketch
  of motion.
• Locate the origin so that it makes your
  calculation simple.
• Coordinate axes can be X-Y or North-South-East-We
  st

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Is your Displacement Positive or Negative?

• Depends on where you place your coordinate axes
• Increasing y or x values are positive
• Decreasing y or x values are negative

y
x
x-
y-
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So what can you do with Time and Distance
Measurements ?

• Calculate Average Speed Distance Traveled
  Average Speed ------------------------
  Time Elapsed Average Speed is always a positive
  number with units.

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Whats Average Velocity?

• Displacement Average Velocity
  ------------------------ Time
  Elapsed

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Average Speed and Average Velocity are Different!

• Speed is a ScalarVelocity is a Vector
• Speed and Velocity are often the same numberbut
  sometimes not.

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Instantaneous Velocity is...

• The average velocity over an infinitesimally
  small period of time.
• Or the average velocity for a given instant.

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When an objects velocity is changing its
Accelerating

• Change in Velocity Average
  Acceleration --------------------
  Time Elapsed

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Acceleration is not Velocity

• Acceleration tells us how fast velocity changes
• Velocity tells us how fast position changes

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Distance-Time Graphs

• AKA d vs. t graphs
• Slope velocity

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Velocity-Time Graphs

• AKA v vs. t graphs
• Slope acceleration

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Acceleration Time Graphs

• AKA a vs. t graphs
• Slope means nothing!

Acceleration
Acceleration
Time
Time