Equal but Opposite

When two forces are opposite in direction and equal in strength, or magnitude, they are called balanced forces. When this happens, the two objects that the forces are acting upon are in equilibrium--this means that neither object moves as a result.

Let’s look at an example of how this works. A book sitting on a table is in equilibrium. The force of gravity is pushing the book down toward the table, and the table is pushing back on the book with the same amount of force in an upward direction.

The force the book has on the table is equal and opposite to the force the table has on the book. These forces are considered to be balanced--they cancel each other out. When forces are balanced, objects do not move.

Push as hard as you can against a wall. If the wall does not move, then it is pushing back with a force equal in magnitude to your pushing, and in the opposite direction of your push. You've just demonstrated balanced forces!