Forces
*You can measure force using the spring
scale at a grocery store.
*A force is measured in newtons.
*one newton is equal to one kilogram
meter per second squared
This picture is an example of the definition of force.
Force
Newton
Push or pull that acts on an object
The measurement of force
*You can us an arrow to represent the
direction and strength of a force.
*Sometimes the net force acting upon
an object is zero when the forces are
equal.
This Picture is an example of unbalanced forces.
Net Force

Overall force acting on an object
after all forces are combined
Friction

A force that opposes the motion
of objects that that touch as they
move past each other
*Examples of balanced forces are very
common
*Often the forces on an object are
unbalanced.
The man is doing work by pushing the block and the result
Is the block moving
Static Friction

The friction force that acts on
objects that are not moving
Sliding Friction

A force that opposes the direction
or the motion of an object
*Gravity is an attractive force that is a
natural part of the earth .
*Momentum doesn’t increase or
decrease.
This is the formula to find the amount of
force acting upon an object.
Rolling Friction

The friction force that acts on an
rolling object
Fluid Friction

Opposes the motion of an object
through a fluid
*Gravity is the weakest universal force.
*Gravity is the most efficient force at a
long distance.
The lawnmower is experiencing
rolling friction because its
wheels are rolling on the
ground.
Air Resistance

Fluid friction acting on an object in
air
Terminal Velocity

Constant velocity of a falling
object when the force of air
resistance equals the force of
gravity.
*Conservation means that something
has a constant value.
*Only when equal and opposite forces
act on the same object do they result in
a net force of zero
This is an example of gravity
because the apple is falling
towards the center of the earth
From the tree.
Projectile Motion

The motion of a falling object after
it is given an initial forward velocity
Gravity

Force that acts on any of wo
masses
*Different types of friction act on moving
and non-moving objects.
*Sliding Friction acts to oppose the
direction of motion.
The stone launched
forward because the
driver stepped on the
brakes too hard and
caused inertia to come
into play.
The cat will fall when the car
stops because there is not
enough force to keep it sitting
in the dashboard.
Inertia

Weight
The tendency of an object to resist  The force of gravity acting on an
a change in its motion
object
*When an object rolls across the floor
both the object and the floor are very
slightly bent out of shape.
*Friction acts on submarines moving
through water and airplanes moving
through air.
This is another example of
an unbalanced force
because the other object
tied to the rope has more
force then the man.
Mass

Measure of inertia an object and
depends on the amount of matter
in the object
Momentum

Product of an objects mass and
velocity
*The force of gravity does not require
contact with objects to be able to act
on them.
*Air resistance and gravity are the only
forces acting on a projectile.
This picture shows the car accelerating
because the wheels are moving faster
and faster over time.
Law of Conservation of
Momentum

If no net force acts on a system
then the total momentum of the
system does not change
Acceleration

The rate at which velocity
changes
*As objects fall to the ground they
accelerate and gain speed.
*An unbalanced force is a result of
forces that are acting on an object not
being equal to each other.
The balls mass
and weight
forms its
momentum,
which carries
through the
other balls to
make the ball on
the opposite
end move.
This cheetah is moving
Very fast and has a high
Velocity.
Velocity

Speed and direction an object is
moving
Instantaneous Speed

Rate at which an object is moving
at any given time
*You can replace sliding friction with
rolling friction.
*Weight does not have an effect in how
fast an object falls if both of the objects
are the same type of object.
The initial forward velocity of the object
Slows as it falls to the ground.
Constant Acceleration

A steady change in velocity
Birds and airplanes face fluid friction in the air
the same way submarined face fluid friction in
the water.
Strong Nuclear Force

Powerful force of attraction that
acts only on the neutrons and
protons in the nucleus
*When you push on something you are
using force.
*Air resistance is the result of fluid friction
in the air.
The object has it’s force located
In it’s center, making it a centripetal
Force.
Centripetal Force

Center directed force that
continuously changes the
direction of an object to make it
move in a circle
Gravitational Force

Is an attractive force that acts
between any two masses