Two Types of Graphs
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Position time graphs
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Velocity time graphs

Position vs. time graphs
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The slope of the graph is equal to the velocity
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If the x/t graph is a straight line
(no curve) then the velocity is constant.
Reference Point….

Position vs. time graphs
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A line with a positive slope indicates positive velocity and the object is moving away from the reference point
A line with a negative slope indicates negative velocity and the object is moving towards the reference point.

Position vs. time graphs

If the line is horizontal (no slope) then the object is stationary (no velocity)

Position vs. time graphs
Accelerated Motion
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If the object is accelerating, the velocity is changing
 x/t graph will no longer be a straight line, but will have a changing slope, resulting in a curve.

Position vs. time graphs

Concave “ Up like a cup ” …the acceleration is positive
Speeding up away Slowing down towards

Position vs. time graphs

Concave “ Down like a frown ” …the acceleration is negative
Speeding up towards Slowing down away

Velocity vs. time graphs
•

The slope is equal to the acceleration.
Positive slope implies an increase in velocity in the positive direction .
• Negative slope implies an increase in velocity in the negative direction .
• Zero slope implies motion with constant velocity .

Velocity vs. time graphs

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Positive velocity indicates the object is moving away from the reference point
The x axis means v=0
Green is slower, getting closer to zero.
Purple is speeding up, moving farther from the x axis.

Velocity vs. time graphs

Negative velocity indicates the object is moving toward the reference point.

Velocity vs. time graphs
(Acceleration)

–horizontal line
– velocity is constant
–acceleration is zero

Velocity vs. time graphs

When the slope of the graph is positive:
– the acceleration is positive

Velocity vs. time graphs

When the slope of the graph is negative:
– the acceleration is negative

Velocity vs. time graphs

We cannot determine where an object ’ s position from a v/t graph, only its
in position.