Balanced Forcesand

Unbalanced Forces

Forces Change Motion

We know that a force is a _____or a _____.

There are many kinds of forces.

Let’s name 3:

•Gravity•Friction•Magnetism

Forces Affect Motion

Look at this car….Many forces are acting here.Many forces are acting here.

• The force of the ground is holding up the car.

• The force of gravity is pulling the car down.

• The force of the engine is turning the wheels.

• The force of friction with the road is holding the car back.

Balanced Forces

Sometimes the forces acting on an object balance each other.

Equal Size Force & Opposite Directions

Balanced Forces

When balanced forces act on an object they do not change the object’s motion or direction.

The net force of balanced objects always equals = O

Unbalanced Forces

• Unbalanced forces occur when one force is greater than its opposite force.

• Unbalanced forces can cause objects to speed up, slow down, stop, or change direction.

Unbalanced ForcesA person riding bike up a

hill may be slowed down by the force of gravity. The forces are unbalanced and the cyclist slows down.

When the cyclist starts down the other side, the unbalanced force of gravity causes the bicycle to speed up.

Can you think of some examples of balanced and unbalanced forces?