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A freely falling object is an object that moves under the influence
of gravity
only. Neglecting air resistance, all objects in free fall in the earth's
gravitational field have a constant acceleration that is directed towards the
earth's center, or perpendicular to the earth's surface, and of magnitude
 g = 9.8 m/s ^{2}. If motion is straight up and down
and we choose a coordinate system with the positive yaxis pointing up and
perpendicular to the earth's surface, we describe the motion with Eq.(2.7),
Eq.(2.8), Eq.(2.9) with
a  g ,
x y .
Equations of Motion for the 1d vertical motion of an object in
free fall:
 v = v_{0}  gt

y = v_{0}t  gt^{ 2}

v^{ 2} = v_{0}^{2}  2gy
Note: Since the acceleration due to gravity is the same for any object, a
heavy object does not fall faster than a light object.
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10/9/1997