Transcript Newton`s Laws of Motion

Newton’s Laws of Motion
Law #1 – Inertia
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An object at rest will remain at rest
and an object in motion will remain
in motion at constant speed and in
a straight line unless acted on by
an unbalanced force.
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This means that unless an
unbalanced force affects an object, it
will continue doing what it is doing –
either sitting still or moving!
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Newton named this law The Law of
Inertia
“Inert” means not moving
So inertia is an object's tendency to stay
still!
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Inertia Depends on Mass

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The more mass an object has, the
harder it is to get it to move or to stop!
This is why seatbelts save people –
they prevent you from maintaining a
speed of 60-70 miles an hour when the
car suddenly stops!
Law #2 - F = m X a

The acceleration of an object
depends on the mass of the object
and the force applied.
Force
Mass
Force
Mass

It is harder to accelerate a more
massive object
Force
Mass
The more force is applied, the more acceleration will occur –
depending on mass!
Force
Mass
For example…

If you throw a bowling ball as
hard as you throw a baseball, it
will not accelerate as much - it
has more mass!
150 N
150 N
This equation works just like
the speed equation…
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If an object accelerates at 10 m/sec with a mass of
50 kg, what is its force?
 F= M x A
 F = 50 x 10
 F = 500 Newtons of force!
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If a 1 kg basketball is thrown with a force of
80 N, what is its acceleration?
If a cow moves with an acceleration of 5
m/sec/sec and has a mass of 200 kg, how
much force is needed?
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Law #3 – Action-Reaction
Force from hot gases
Whenever one
object exerts a
force on a second
object, the second
object exerts an
equal and opposite
force to the first.
Forward thrust
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All forces act in pairs!
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Whenever one force acts, a second must act.
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THIS IS TRUE FOR EVERY FORCE IN THE
UNIVERSE!!!

When you jump off of the ground, you push down
and the ground pushes you back up.

If an astronaut floats away from his ship, he can
throw a wrench in the opposite direction, and be
propelled back toward the ship.