Position

Definition: Position

Let $\mathcal{R}$ be some reference frame with origin $O$.

The position of a particle $p$ is the vector which points from the origin $O$ to the point in space where $p$ is located.

NOTATION

$$\mathbf{r}\mathbf{r}\vec{r}$$

In physics, we usually want to express the position of a particle as a function $\mathbf{r}:\mathbb{R}\to \mathbb{R}$ of time because we want to see how it changes with time.