College and Engineering Physics
Acceleration
Acceleration
Motion with Constant Acceleration
Instantaneous Acceleration
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Acceleration
G
a
College and Engineering Physics
Acceleration
Acceleration measures the change in the motion of an object
This change can happen in magnitude or direction.
As the bee moves to a new flower, he speeds up at takeoff and
slows down as he lands.
Both speeding up and slowing down are acceleration.
As he leaves the scene, his speed is constant, but his direction
changes.
This change in direction is also an acceleration!
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College and Engineering Physics
Acceleration
Average Acceleration
The direction and quantity of “the change of motion” of a particle is given by
its acceleration.
vx
The slope of this line is
the x-component of the
average acceleration.
∆vx
∆t
t
The average acceleration of a particle (whether or not the change in motion
is uniform) is given be a simple equation …
G
∆v
G
aavg =
∆t
3
In words, we would say this equation tells us that “the average acceleration
of a particle is the change in its velocity over the interval during which it
moved”.
College and Engineering Physics
Acceleration
Motion with Constant Acceleration (Uniform Change in Motion)
If the velocity vs. time graph of a
particle’s motion is a straight line,
then the average acceleration is the
slope of this line and this
component of the change in motion
is uniform.
vx
∆vx
∆t
t
Acceleration is constant if it does not change.
This means that the quantity (known as the magnitude) and the direction
stay the same.
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College and Engineering Physics
Acceleration
Acceleration vs. Time Graph
G
a vs. t
A way to model the change in motion of a particle is to graph acceleration
vs. time.
Acceleration is the derivative (slope) of the velocity over time.
ax
vx
t
t
0s 1s 2s 3s 4s 5s 6s 7s 8s
0s 1s 2s 3s 4s 5s 6s 7s 8s
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