Every object will either maintain its motion due to balanced forces or accelerate due to unbalanced forces. These forces come in many forms, but each act as a push or pull on the object. Since forces are vectors, equal forces acting in opposite directions will cancel each other out. Newton’s First and Second Law of Motion provide the framework in which we analyze balanced and unbalanced forces.
The general categories of forces that we look at are contact forces, which come into play when an object is touching another, such as tension, friction, the normal force or any applied force. There are also action-at-a-distance forces that do not require the objects to be touching, but can act through empty space, such as the gravitational force or electromagnetic force. Each of these has a set of equations that helps us to calculate the force. Forces acting at an angle can be split into their horizontal and vertical components, so that the vertical and horizontal directions can be analyzed separately, and the results can be recombined using basic right-angle trigonometry.