Feynman diagrams have had a huge impact in physics ... that replaces the index notation. They represent a vector as a box with a line attached to it. By contrast, a scalar has no lines extending ...

are used to describe situations where several forces act on an object. Vector diagrams are used to resolve (break down) a single force into two forces acting at right angles to each other.

The sum of these two forces can be found using a vector diagram. The two forces are represented by the adjacent sides of a parallelogram, the lengths of the sizes being proportional to the size of ...