Vectors are useful!

Graphic - newtontwo

The laws of physics are often most simply and powerfully expressed using vectors.

Newton’s 2nd Law provides an example. The equation

\[ \vec{F}= m\vec{a} \]
relates one vector, $\vec{a}$ (the acceleration of a body) to another vector, $\vec{F}$ (the force the body experiences). This equation thus relates both the magnitudes and the directions of the two vectors.