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# Free Fall and Graphs of Motion by liaoqinmei

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• pg 1
```									 Free Fall
and Graphs
of Motion
A Falling Apple
 Consider   an apple falling
from a tree
 It starts from a position of
rest and gains speed as it
falls.
 Gravity causes the apple to
accelerate as it falls.
Free Fall
 Describes  objects that are only
affected by gravity.
 The speed of an object in free
fall increases or decreases by
9.81 m/s each second.
 9.81 m/s2 is the acceleration
due to gravity.
 “g” represents the acc. due to
gravity
Straight Up
 Now    consider an object
tossed straight up.
 As an object moves upward,
it is accelerating (speed ).
- the object slows at a rate of
9.81 m/s2 (acc due to
gravity).
The highest point
 At its highest point, the
object has an inst. speed of
zero (b/c it has to stop to
change directions)
 The object will fall as if it
were dropped from its
highest point.
The way down
 As the object is falling, it will
accelerate at 9.81m/s2
 The falling object will its
speed by 9.81m/s each
second.
Height and Velocity
 The  inst. speed
at points of
equal
elevations are
the same.
 The velocities
are different
b/c they are in
opposite
directions.
Air Resistance & Free Fall
 Causes   objects of different
shapes to accelerate
differently (stone vs feather)
 With negligible air resistance,
falling objects can be
considered freely falling.
The path is
symmetrical.
Acceleration is
constant.
The magnitude
of the velocities is
the same at equal
heights.
Group Discussion
Two stones are thrown from a cliff at
the same time with the same speed,
one upward and one downward.
Which stone, if either, hits the ground
first? Which, if either, hits with the
higher speed?
In a group discussion, make your
best argument for each possible
prediction. Set up numerical
examples and solve them to test your
prediction.

```
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