Acceleration Rarely does Velocity remain the same

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AccelerationRarely does Velocity remain the
same
A velocity of a ball rolling down a ramp will
increase
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AccelerationRate of change of Velocity (change
in velocity over a given time interval)We are
still working in one DimensionAcceleration can
be in both directions, that is, positive or
negative
Uses the same chosen frame of reference we use
for position and velocity
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Graphing Observations Velocity vs. Time
Consider an object moving with its velocity
increasing linearly on a velocity vs. time graph
What does the slope of this line represent?
Velocity (m/s)
v3
c
v2
c
v1
c
Time (s)
t1
t2
t3
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Graphing Observations acceleration vs. Time
If velocity is increasing linearly, acceleration
will be a horizontal line on an acceleration vs.
time graph
acceleration (m/s)
c
c
c
Time (s)
t1
t2
t3
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Acceleration and Velocity
Acceleration has a magnitude and direction Its
direction may be different from velocity! Units
of acceleration meters per second-squared
or m/s2
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Graphing Observations
The slope of the line on a velocity vs. time
graph gives average acceleration This line can
have a positive or negative slope
Positive acceleration
Velocity (m)
Zero acceleration (velocity unchanging)
Negativeacceleration
Time (s)
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Acceleration Problems
Do problems p 49 Practice 2B 1-4
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Constant Acceleration
In this case the point exactly halfway between vi
and vf is considered to be the average velocity
Velocity (m/s)
Note Only for uniform acceleration
vf
c
vavg
c
vi
c
Time (s)
t1
t2
t3
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Displacement with Constant Uniform Acceleration
Equation

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Constant Uniform Acceleration Problems
Solve several problems using the constant uniform
acceleration equation Practice 2C 1-2 Homework
Practice 2C 3-5
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Displacement with Constant Uniform Acceleration
Equation

Substitute vf vi a Dt into ?x ½ (vi vf)
?t Rearrange to get ?x vi ?t ½ a (Dt)2 This
equation can be used to solve for a number of
problems
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Corresponding Acceleration, Velocity, Position
Graphs
Acceleration (m/s2)
Velocity (m/s)
What is general equation for Position?
Position (m)
Time (s)
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Acceleration Problems
Do Practice 2D 1,2,3
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Acceleration
What acceleration, that is, what acceleration
vector do we experience daily? What direction
does it have?
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Final Velocity After Any Displacement Equation

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Acceleration Problems
Do Practice 2E 1,2,3