Balanced and Unbalanced Forces When two or more forces are acting on an object and they are not equal in size, we say the forces are unbalanced. Unbalanced forces cause a change in the motion of an object. An apple falling from a tree demonstrates an unbalanced force. A force is a push or a pull. Many different forces act on objects around us all the time. Balanced Forces If the forces on an object are unbalanced, then the object will do one of the following: Start moving Stop moving Change directions Slow down Speed up If the forces on the object are balanced, then the object doesn’t move. When two forces acting on an object are equal in size, but opposite in direction, we say the forces are balanced. Balanced forces do not cause a change in motion. A book sitting on a table demonstrates balanced forces. Force Diagrams We can show the forces acting on an object in a force diagram. In a force diagram, the larger force is shown with a bigger arrow, and the smaller force is shown with a smaller arrow. The arrows also show the direction the force is acting in. Force is measured in Newtons, and some force diagrams will label the force with the number of Newtons. Force diagrams allow us to predict the direction and movement of an object. The most important thing to remember is moving objects are unbalanced, objects that are not moving are balanced.