Accelerated Motion

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Chapter 3 Accelerated Motion
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3.1 Acceleration
Acceleration is the rate of change In velocity
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Velocity and Acceleration
vi a Motion
Speeding up
- - Speeding up
- Slowing down
- Slowing down
or - 0 Constant
0 - Or Speeding up from rest
0 0 Remaining at rest
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Average acceleration is the Change in velocity
during some Measurable time interval.
vf vi tf ti
?v ?t
a

The SI unit for acceleration is m/s2
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Problems...
A sprinter begins a race at 0.0 m/s And finished
at 4.0 m/s. He does This in a time of 8s. What
is his acceleration?
0.5 m/s2
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Instantaneous acceleration is The change in
velocity at An instant of time.
A velocity-time graph is a graph That show
velocity on the X-axis and time on the y-axis.
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The slope of a V-T graph will Give you
acceleration.
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3.2 Motion with Constant Acceleration
There are a bunch of new formulas That can be
found by deriving Them from the two basic
formulas That we already know.
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Displacement with Constant Acceleration
?d ½ (vi vf)?t
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Problems...
A racing car reaches a speed of 42 m/s. It then
begins a uniform Negative acceleration, using
its Parachute and brakes, and comes To a stop
5.5s later. Find how far The car moves while
stopping.
120 m
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Velocity with Constant Acceleration
vf vi a?t
Displacement with Constant Acceleration
?d vi?t ½a(?t)2
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Problems...
A plane starting at rest at one end Of a runway
undergoes a constant Acceleration of 4.8 m/s2 for
15s Before takeoff. What is its speed
at Takeoff? How long must the Runway be for the
plane to Take off?
72 m/s
540 m
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Final Velocity after Any displacement
vf2 vi2 2a?d
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Problems...
A babysitter pushing a stroller Starts from rest
and accelerates At 0.500 m/s2. What is the
Velocity of the stroller after it Has traveled
4.75 m?
2.18 m/s
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Equations for constantly Accelerated straight
line motion
Form to use when accelerating object has initial velocity. Form to use when accelerating object starts from rest.
?d ½ (vi vf)?t ?d ½(vf)?t
vf vi a?t vf a(?t)
?d vi?t ½a(?t)2 ?d ½a(?t)2
vf2 vi2 2a?d vf2 2a?d
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3.3 Free Fall
Free fall is the motion of an Object falling
with a Constant Acceleration due To gravity.
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All free falling bodies undergo A uniform
acceleration Of 9.81 m/s2.
This acceleration, a, is given The new symbol, g.
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Problems...
A construction worker accidentally Drops a brick
from a high scaffold. What is the velocity of the
brick After 4 seconds? How far does the Brick
fall during this time?
78 m
39 m/s
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THE END
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