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Science Unit One
Forces and Motion
What does it take to make an object
move?
FORCE - A push or a pull
that acts on an object
Forces are needed to set objects
into motion
Forces that can push or pull on objects
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Contact or Non-contact forces
Gravity
Friction
Air
Magnetic Forces
2 KINDS OF FORCES
• BALANCED FORCE
–When all of the forces on an
object cancel one another out
• UNBALANCED FORCE
–When a certain force is
partially or not at all cancelled
out by other forces
Balanced Forces
Balanced Forces with a Balloon
• The inward push of the stretched rubber is
balanced by the outward push of the air.
Outside push of air
Inside push of air
• Now let’s take a look at unbalanced forces!
• Remember…
• UNBALANCED FORCE
–When a certain force is
partially or not at all
cancelled out by other
forces
Unbalanced Force
• Example of unbalanced force on a balloon
Let’s explore
• Working with a partner, your job is to find
ways to show the class an example of a
balanced force and an unbalanced force.
• You may use each other and common objects
found in the room.
• Remember to be respectful of each other and
of the things in this room.
• You have 10 minutes to brainstorm.
Let’s Explore…
Plate and tablecloth
If______________________ then____________
Reason?
Marble and cup
If _____________________then_____________
Reason?
INERTIA – the tendency of
an object to resist a change
in its state of motion
• If something is “not moving,” like a car, it
wants to stay “not moving.”
• If a marble is rolling down the hall, it wants to
keep rolling down the hall.
NEWTON’S FIRST LAW OF MOTION
An object at rest will remain at rest
and an object in motion will remain
in motion unless acted upon by an
unbalanced force.
This is also called the LAW OF
INTERTIA.
• Show videos online of Newton’s First Law
Assignment
• Using your notes, complete
the review sheet, Newton’s
First Law
FRICTION – A force that
opposes the motion of
one object moving past
another
GRAVITY – the name for the
attractive force between the
mass of Earth and the mass
of objects on Earth
• SPEED
• How fast an object’s position
changes with time at any
given moment
• Speed = d/t
(distance divided by time)
• VELOCITY
• The speed and direction of
a moving object
• ACCELERATION
• Change in velocity with respect
to time
• DECELERATION
• When a force causes the speed
of an object to decrease
We have learned all about
forces and Newton’s First Law of
Motion!
Now, let’s look at Newton’s Second
Law of Motion…
• FORCE is the push or pull
that acts on an object.
• MASS is the matter that
makes up an object.
• ACCELERATION is a change in
velocity with respect to time.
Newton’s Second Law of Motion
Force = Mass x Acceleration (F = m x a)
The acceleration of an object depends
on its mass and the size of the force
applied to it.
Experiment time…
• Bill Nye video on Newton’s laws
• Newton’s Third Law of Motion
–For every action there is an
equal and opposite reaction.