Transcript Gravity and Motion All objects fall with the same acceleration Galileo

Gravity and Motion
All objects fall with the same
acceleration
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Galileo proposed that all
objects will land at the
same time when they are
dropped at the same
time from the same
height.
Acceleration due to
gravity is the same for all
objects
All objects accelerate
toward Earth at a rate of
9.8 m/s/s.
Air resistance slows down
acceleration
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Air resistance occurs
between the surface
of the falling and the
air that surrounds it
Air resistance affects
some objects more
than others
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Depends on size
and shape
Acceleration stops at terminal
velocity
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Terminal velocity
– objects that fall
at a constant
velocity
 Ex: Sky diver
and a
parachute
Free fall occurs when there is no air
resistance
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Free fall – gravity is
pulling it down and no
other forces are
acting on it
Because of air
resistance (fluid
friction) free fall can
occur where there is
no air – in a vacuum
(a place in which
there is no matter) or
in space
Orbiting objects are in free fall
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It is impossible to be
“weightless” anywhere in
the universe
Weight is a measure of
gravity, and it acts on all
matter, and everything is
made of matter
Astronauts “float” in
orbiting spaceships
because of free fall
Two motions combine to cause
orbiting
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An object is said
to be orbiting
when it is traveling
in a circular or
nearly circular
path around
another object
Moving forward
and always falling
The role of gravity in orbiting
Any object in circular motion is
constantly changing direction
 Centripetal force – the unbalanced
force that causes objects to move
in a circular path
 Gravity provides the centripetal
force that keeps objects in orbit
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Projectile motion and gravity
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Projectile motion – the curved path an
object follows when thrown or
propelled near the surface of the
Earth
Two components
 Horizontal motion: The forward
motion of the object
 Vertical motion: the gravitational
pull of earth