what is force

In physics, a force is an influence that can cause an object to change its velocity, i.e., to accelerate, meaning a change in speed or direction, unless counterbalanced by other forces. The concept of force makes the everyday notion of pushing or pulling mathematically precise. Because the magnitude and direction of a force are both important, force is a vector quantity. The SI unit of force is the newton (N), and force is often represented by the symbol F. Force can be a push or pull upon an object resulting from the object's interaction with another object. It has both magnitude and direction, and it is a vector quantity. There are two broad categories of forces: contact forces and action-at-a-distance forces. Contact forces result when two objects are physically contacting each other, while action-at-a-distance forces result even when the two interacting objects are not in physical contact with each other. Examples of forces include frictional forces, tensional forces, normal forces, air resistance forces, and applied forces