Physics

The Five Force Equation

Presented by Denise Jenke

Newton’s Second Law of Motion

Fnet = maWhat does it mean?

What do the symbols stand for?

How does this relate to the Five Force Equation?

Fnet = net force

Fnet = maWhat does it mean?

A net force causes a mass to accelerate

Fnet = ma

What do the symbols stand for?

Fnet = net force; the vector sum of all forces acting on an object (Newton-N)

m = mass (kilogram-kg)

a = acceleration; the rate of change of velocity (m/s2)

The Five Force Equation

Fnet = Fg + Fn + Fa + Ff

BUT…..what does it mean????

Fg

Fn

Ff Fa

Fnet = Fg + Fn + Fa + Ff

Fg = gravitational force

Force due to the Earth’s gravity on the object

Always down

Fg

Fnet = Fg + Fn + Fa + Ff

Fg = mgg = acceleration due to the Earth’s gravity (-9.8 m/s2)

Fg

Fnet = Fg + Fn + Fa + Ff

Fn = normal force

The force of the surface on the object

Support forceFn

Fnet = Fg + Fn + Fa + Ff

Is normal force the action/reaction force of gravitational force?

Fn

Fg

Fnet = Fg + Fn + Fa + Ff

Fa = applied force

Push or pull on an object

Force applied to the object

Force can be applied in any direction

Fa

Fnet = Fg + Fn + Fa + Ff

Ff = force of friction

Force that opposes the motion of an object

Ff

Fnet = Fg + Fn + Fa + Ff

Friction is caused by the rubbing of two surfaces

Surfaces must be touching and must want to move

Ff

Fnet = Fg + Fn + Fa + Ff

Types of Frictional Force:

Static Friction

Sliding Friction

Ff

Static Friction

Frictional force between two object in contact that keep them stationary (relative to each other)It is the force that keeps objects from movingForce acts parallel to direction of motionOnly exists if a force is being applied to one of the objects

Sliding Friction

Frictional force between two objects in contact and in motion (relative to each other)

It is the force that acts when objects are moving

Force acts parallel to the direction of motion

The Five Force Equation

Fnet = Fg + Fn + Fa + Ff

BUT…..what does it mean????

Fg

Fn

Ff Fa

The Five Force Equation

SO….

Which forces cause motion?

Which forces cause acceleration?

Fg

Fn

Ff Fa

The Five Force Equation

Stay tuned for.. Using the Five Force Equation

Fg

Fn

Ff Fa