Download Newton`s Laws 1.The First Law: Force and Inertia 2.The Second Law

Newton’s Laws
1.The First Law: Force and Inertia
2.The Second Law:
Force = Mass x Acceleration
3.The Third Law:
Action and Reaction
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Objectives – today & tomorrow
1)Describe how the law of inertia affects the
motion of an object.
2)Describe balanced and unbalanced forces.
Calculate the net force for two or more
forces acting on an object. Review examples.
3)Measure and describe force in terms of
newtons (N). Explain where the unit of force
a newton (N) comes from.
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The First Law:
Inertia states that a body at rest
will stay at rest and a body in
motion will stay in motion, unless
acted on by an unbalanced force.
Newton’s First Law Video http://my.hrw.com/sh2/sh07_10/student/flash/visual_concepts/70587.htm
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Force: is an action that can change motion.
A force is what we call a push or a pull, or
any action that has the ability to change an
object’s motion.
Forces can be used to
increase or decrease the
speed of an object, or change
the direction of motion.
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Inertia: is the term used to describe an object’s
ability to resist any change in its state of motion.
An object with a lot of inertia takes a lot of
force to start or stop it. Meanwhile an object
with less inertia requires a small amount of
force to start or stop.
Inertia is a property of matter. A body will keep
moving at a constant speed and in the same
direction until an unbalanced force acts on it.
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Which systems in a car overcome the law of
inertia and how? “Take a moment to fill in blanks.”
The _________ supplies force that allows you
to change motion by pressing the gas pedal.
The _________are designed to help you
change your motion by slowing down.
The ___________is designed to help you
change your motion by changing your
direction.
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What happens in a crash? Inertia can explain what
happens in a car crash.
When a car traveling about
40mph collides head-on with
something solid, the car
crumples, slows down, and stops
within approximately 0.1 s.
Any passenger not wearing a safety belt continues
to move forward at the same speed the car was
traveling.
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Q1
A force is a ___________.
A force is a push or pull. Forces, such as the
force of the atmosphere against a person’s body,
are not always noticeable.
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Q 2 - When are forces on an object balanced?
When forces are equal in size and opposite
in direction, they are balanced forces, and
the net force is zero. The object is at rest.
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Q3 - Inertia is ……
A. the tendency of an object to have a positive
acceleration
B. the tendency of an object to resist any
change in its motion
C. The tendency of an object to have a net
force of zero.
D. The tendency of an object to change in
speed or direction.
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NEXT
Complete / see Mental Map of
Force = mass x acceleration
Where does the SI Unit of Force (N) for
newton named after Sir Isaac Newton
come from and how is it built?
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