Unbalanced Forces
-Forces that cause a change in the motion of an object are unbalanced forces.
-Unbalanced forces are not equal and opposite.
Ex:Two football players blocking each other, then one tackles the other.

Balanced Forces
-Forces that are equal in size but opposite in direction are called balanced forces.
-Balanced forces do not cause a change in motion, and the speed will be the same.
Ex:Two cards leaning against each other and not falling over.

The Net Force
-The combination of all the forces acting on an object is the net force.
-When more than one force is acting on an object, the net force determines the motion of the object.
Ex:The force of gravity is pulling the book downwards, while the muscles in your arm force the book upwards,and the velicity will change.