-Speed and Velocity -Uniform Linear Motion

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-Speed and Velocity-Uniform Linear Motion

• Physics
• Mrs. Coyle

http//www.wallpaperbase.com/wallpapers/sports/for
mula1/formula_1_3.jpg
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Speed and Velocity

• Average Speed Total Distance Travelled
• Time
• vd/t (Scalar)
• Average Velocity Displacement
• Time
• v Dd / D t
• (d2-d1) / (t2- t1) (Vector)

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Vectors and Scalars

• Scalar ? Magnitude (size)
• Vectors ? Magnitude and Direction

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Example

• A car is travelling at an average velocity of
  55km/h, N, when the driver sees a box on the
  road. If the reaction time of the driver is
  0.45sec, how far does the car travel at that
  velocity before the driver even begins to break?

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Instantaneous SpeedInstantaneous Velocity

• Instantaneous Speed
• Speed at a given instant (ex speedometer of
  car)
• Instantaneous Velocity
• Velocity at a given instant
• Instantaneous speed is the magnitude of
  instantaneous velocity.

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Note

• Average speed is equal to
• the magnitude of average velocity
• ONLY
• when velocity is CONSTANT (magnitude and
  direction).

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Uniform Linear Motion

• Motion with constant velocity
• Straight line
• Same direction

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If the speed on this ride is constant, is the
motion uniform linear motion?
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Graphs of Motion -Position-Time
-Velocity-Time -Acceleration-Time
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Example Position vs Time for Uniform Linear
Motion
Position (m)
o
Time (s)
Note The slope of the line in a Position-Time
Graph equals the average velocity.
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Example Velocity vs Time for UniformLinear
Motion
Velocity (m/s)
o
Time (s)
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Example Position vs Time Graph
Position, (m)
20.0
10.0
A
o
1.0
0.5
1.5
2.0
Time, (s)

• What is the avge velocity at the time intervals
• (0s-1s) (1s-1.5s) (1.5s-1.7s) (1.7s-2.0s)
• Draw the velocity time diagram.

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Note

• The area under the line (curve) of a
  velocity-time graph is equal to the displacement
  of the object during that time interval.