Question

What is angular displacement?

Answer 1

It is the displacement considered as a change in angular position with respect a certain reference.

Explanation:

It may seem complicated but when you have a rotational motion it can be useful to consider, instead of a linear, an angular displacements involving angles. Have a look:

as you can see together with the linear displacement `s` normally measured in meters you have a correspondin angular displacement given as:

`Deltatheta=theta_2-theta_1` normally measured in radians.

The two are related through the radius `r` as:

`s=r*Deltatheta`

Hope it helps.