What is force? Force is a push or a pull, it include size and direction. The unit of force is n, which represent newton, and named by the scientist Isaac Newton. Force occur on object, meaning that you when you push, an object must receive it. But when force is happening, it doesn’t mean that motion will also occur. Motion is when an object move. Force is separated into two kinds, balance and unbalance.
When a force to object is balance, the object will not move. Like the example shown in the below picture, the table will not move because of the reaction force of the table and the weight of the metal block.
When a force is unbalance, the object will move. For example, because there are unbalance force (80n and 40n), the force will bigger n will make the wagon move the the direction it is pushing/pulling.
Citations:
http://eschooltoday.com/science/forces/balanced-forces.html
http://eschooltoday.com/science/forces/unbalanced-forces.html