Transcript Science PowerPoint Ch 6 Sec 1

Physical Science
Chapter 6
Forces & Motion
Section 1
Gravity and Motion
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Objs fall to the ground at the same rate
because the acceleration due to G is the
same for all objs
Acceleration depends on both force & mass
A heavier obj experiences a greater G force
than a lighter obj does
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But a heavier obj is also harder to accelerate
because it has more mass.
The xtra mass of the heavy obj exactly balances
the additional gravitational force.
Acceleration Due to Gravity (G)
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Acceleration is the rate at which velocity
changes over time.
The A of an obj is the obj’s change in V
divided by the amount of time (T) during
which the change occurs
All objs accelerate toward earth at a rate of
9.8 meters per second squared
Velocity of Falling Objects
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V=g x t
The change in velocity is the diff between the
final velocity and the starting V.
Orbiting Objs Are in Free Fall
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Weight is a measure of gravitational force
The size depends on the mas
Free fall—the motion of a body when only the
force of gravity (G) is acting on the body: no
air resistance
2 Motions Combine to Cause Orbiting
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An obj is orbiting when it is traveling around
another obj in space
When a spacecraft is orbiting earth, it is
moving forward
Orbiting and Centripetal Force
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Any obt in circular motion is constantly
changing direction
An unbalanced force is necessary to change
the motion of any obj, there must be an
unbalanced force working on any obj in
circular motion
The unbalanced force that causes objs to
move in a circular path called a centripetal
force.
Projectile Motion & Gravity
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PM is the curved path an obj follows when it
is thrown or propelled near the surface of the
Earth
PM has 2 components: horizontal and
vertical motion.
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They are independenct of each other and have no
effect on each other
When they are combined, they form a curved path
Horizontal Motion
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E.G., throwing a ball
There are NO forces to change the ball’s
horizontal motion
Vertical Motion
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G pulls everything on E downward toward the
center of E.
G pulls a thrown ball downward & gives the
ball vertical motion.
Acceleration occurs at 9.8 m/s squared