# Angular displacement

An object moving in circular motion traces the arc of a circle. The angle between the radii at the beginning and the end of the arc (the angle subtended by the arc) is the angular displacement $$(\theta)$$ of the object.

This is given by $$\vecphy{\theta}=\frac{\vecphy{s}}{r}$$, where $$s$$ is the arc length and $$r$$ is the radius of the arc.

Angular displacement can be thought of as a vector, but for simplicity it is usually considered to be a scalar.

The SI unit of angular displacement is the **radian $$(\text{rad})$$**. One radian is $$180/\pi$$ degrees.

The angular displacement can exceed $$2\pi\text{ rad}$$, which means that more than one revolution has been completed. The angular displacement can therefore be thought of as an angular "distance."