Force (physics).

In physics, force is characterized as any influence or interaction by one object on another object, which results in force being exerted on both objects, as well as changes in the motion and the velocity. Velocity is defined as the rate at which a physical object changes position. When the velocity of an object is changing, the word "acceleration" is used. For example, the action involved in pushing a door open or pulling it closed serves as the force that influences the door to change its velocity (to accelerate or decelerate) and its direction. Force is measured in units called Newtons, and the total amount of force (F) can be determined by multiplying an object’s mass (m) by the amount of its acceleration (a), expressed by the equation F = ma.