Forces: Gravity, Inertia and Friction
S8P3: Students will investigate the relationship between force, mass, and the
motion of objects.
b. Demonstrate the effect of balanced and unbalanced forces on an object
in terms of gravity, inertia and friction.
S8P5: Students will recognize characteristics of gravity, electricity, and
magnetism as major kinds of forces acting in nature.
a. Recognize that every object exerts gravitational force on every other
object and that the force exerted depends on how much mass the objects have
and how far apart they are.
Must Know
Vocab
Force
Balanced force
Unbalanced force
Picture Clue
Definition
A push or a pull
A force that does not
result in motion; the
forces are equal in size
and opposite in
direction.
A force that results in a
change in motion; the
forces are not equal or
opposite.
Stationary
Not moving.
Rest
An object is said to be at
rest if it does not change
its position with respect
to its surroundings.
Gravity
A force of attraction
between all objects. The
force of gravity depends
on size and distance.
Must Know
Vocab
Picture Clue
Definition
Friction
The force of
resistance/opposition
to motion between
two objects.
Inertia
An object in motion
stays in motion until
an outside force
causes it to stop.
Work
The transfer of
energy.
Newton
A unit of force.
Net Force
The sum of all forces
acting on an object
Kinetic Friction
Friction that acts between two
objects that are in motion
Must-Know
Words
Static Friction
Mass
Weight
Displacement
Motion
My Picture Clue
Definition
Friction that acts between two objects that are
not in motion.
The amount of matter in an object.
A measurement of the force of gravity acting
on an object. More mass=more gravity. Closer
distance=more gravity.
Change in relative position of an object.
an object’s change in position relative to a
reference point
Must Know
Vocab
Picture Clue
Definition
Sir Isaac Newton
Scientist famous for developing the
laws of motion. He is most famous for
“discovering” gravity.
Newton’s 1st Law
An object at rest will remain at rest
unless acted on by an unbalanced
force. An object in motion continues in
motion with the same speed and in the
same direction unless acted upon by
an unbalanced force.
This law is often called
"the law of inertia".
Newton’s 3rd Law
For every action there is an equal and
opposite reaction.
Learning Targets:
1. I can differentiate between balanced and unbalanced
forces.
2. I can explain how unbalanced forces cause a predictable
change in the motion of an object.
3. I can analyze a situation and calculate the net force of the
object.
4. I can describe gravity as a force and explain how it is affected by mass and
distance.
5. I can describe the difference between mass and weight.
6. I can describe Newton’s First Law of Motion and how it relates to objects at rest
and objects in motion.
7. I can state Newton’s Third Law and give example of force pairs.
8. I can explain why friction occurs, and describe the two types of friction.
9. I can identify ways in which friction is helpful or harmful.