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State and give
examples of
momentum and
Newton’s 3rd Laws
of Motion
Practice using these
new concepts.
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Newton's third law
momentum
impulse
law of conservation
of momentum
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Momentum- amount of force needed to stop
a moving object, it’s always conserved; never
lost–
FORMULA
p= mass x velocity
EX: a ball is 10 kg, and its velocity Is 5 m/s
so momentum = 10g x 5m/s = 50 kg m/s
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60-kg halfback moving eastward at 9 m/s.
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1000-kg car moving northward at 20 m/s.
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40-kg freshman moving southward at 2 m/s.
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Bill Nye Momentum
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Action – Reaction
 Forces are always produced in pairs with opposite
directions & equal strengths
 For every force there is an equal and opposite
force
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Newton's Third
Law Action
Reaction
The truck is in motion. What is the force
that causes it to stop?
The push of the stopped car.
The car is at rest. What is the force that
causes it to move?
The push of the truck.
What about the ladder on top of the truck?
The ladder is in motion because the truck is in
motion.
When the truck stops, the ladder stays in motion.
The truck is stopped by the force of the car, but the
ladder is not.
What force stops the ladder?
Gravity.
The truck is in motion, the car is at rest. How do
each of these vehicles accelerate?
The truck stops moving. The car starts moving.
Which one will be the hardest to accelerate?
The truck because it has the most mass.
Why does the car move [accelerate] when it is hit
by the truck?
The heavy and moving truck has more force than
the small, at rest car.
Why does the truck stop moving when it hits the
car?
The force of the car pushing back on the truck,
plus the force of friction between the massive truck
and the road slow down, the stop the truck.
The truck hits the car. An action force stops the
truck.
What is the equal and opposite reaction force?
The force that pushes the car forward.
Warner Brothers cartoon character
Wile E. Coyote often finds himself
falling off a cliff. Then a giant
boulder usually lands on top of him
after he hits the ground. If Wile E.
Coyote and a boulder fall off a cliff
at the same time, which do you think
will hit the ground first?