# 8th & 9th Forces and Motion

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I can conceptually and mathematically
describe forces and motion.
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Distance is the length of a path between two
points.
Displacement is the direction and distance
between a beginning point and an ending
point.
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Sometimes it is necessary to combine
displacements mathematically.
We can do this by using vectors.
A vector is a quantity that has a magnitude
(how much) and direction.
A scalar is a quantity that has a magnitude
without a direction.
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Speed is how fast something moves.
There are 2 ways to describe the speed of an
object:
◦ a) average speed
◦ b) instantaneous speed
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Average speed is the average value of speed
for an object over the entire duration of the
trip.
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The mathematical equation for
average speed is:
Average Speed = Total Distance
Total Time
v=d
cccct
V  speed
d  distance
t  time
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Instantaneous Speed is the speed measured
at a particular instant in time.
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Distance and time can be displayed on a
distance-time graph.
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Speed is the slope of a line on a distancetime graph.
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Velocity is speed with a direction.
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For example:
◦ the speed of a Camaro may be 75 miles per hour,
◦ the velocity may be 75 miles per hour EAST.
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Acceleration is the rate at which velocity
changes.
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Acceleration is a vector.
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Acceleration can be described as a change in:
◦ Speed
◦ Direction
◦ or both
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Free fall is when an object falls towards Earth
due to earth’s gravity.
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Objects falling near Earth’s surface accelerate
downward at a rate of 9.8 m/s2
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You can calculate the acceleration of an
object by dividing the change in velocity by
the total time:
Acceleration = change in velocity
total time
= (v2 – v1 )
t
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Acceleration is the slope of a speed-time
graph.
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Average acceleration is a measure of the
average value for the acceleration of an
object over a given amount of time.
Instantaneous acceleration is a measure of
the acceleration of an object at any given
instant in time.
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I can conceptually and mathematically
describe forces and motion.
```