Angular acceleration is the rate of change of angular velocity.It is measured in radians per second squared (rad/s2).
From Newton’s second law, α = T / I
I =Mass moment of inertia of the body, T = Total torque exerted on the body.
For example, when Total torque(in rad/sec) is 3, Mass moment of inertia(in sec) is 6, then Angular Acceleration = 0.5 rad/s2.