Introduction

In circular motion, angular acceleration is the rate with which the angular velocity changes with time. It is also referred to as rotational acceleration. It is a vector quantity, that is, it has both magnitude and direction.

Angular acceleration is denoted by

α�. 

If

θ� is the angular displacement,

ω�is the angular velocity and

α�, the angular acceleration, then;

α=dωdt=d2θdt2�=����=�2���2 (as;

ω=dθdt�=����)

The above formula gives the instantaneous angular acceleration.

If

ΔωΔ� is the change in angular velocity over a time interval

ΔtΔ�, then average angular acceleration is given by:

α=ΔωΔt�=Δ�Δ�

In the case of uniform rotation, the average and instantaneous values coincide.

It is expressed in the units of rad/s² or radians per second squared.