A Net force (also known as a resultant force) is a vector produced when two or more forces act upon a single object. It is calculated by adding the force vectors acting upon the object.

• When force A and force B act on an object in the same direction (parallel vectors), the net force (C) is equal to A + B, in the direction that both A and B point.

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• When force A and force B act on an object in opposite directions (180 degrees between then - anti-parallel vectors), the net force (C) is equal to |A - B|, in the direction of whichever one has greater absolute value ("greater magnitude").

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• When the angle between them (the forces) is anything else, then the individual components must be added up using sine and cosine.

(Note: the illustration assumes that the object, in this case a square, has no center of mass and can be treated like a point.)