The Physics Department - Mechanics, Forces
A force can most easily be described as a push or a pull. When a force is applied to an object, the velocity of that object changes. This change in velocity constitutes an acceleration. So, forces are tied to accelerations. Galileo and Newton were scientists who developed our understanding of forces.
Galileo and the Concept of Inertia
Isaac Newton's Three Laws of Motion
An understanding of forces should include and understanding of vectors.