Angular acceleration

This article is about the analogue, from linear motion to angular motion, of: acceleration

Definition

The angular acceleration of a rigid body is defined as the second derivative of its angular displacement with respect to time.

Angular acceleration is a vector. The line of the vector is the same as the axis of rotation, the magnitude is the angular acceleration, and the direction depends on the sense of acceleration (clockwise or counter-clockwise). The relevant rule here is the right-hand thumb rule: clockwise rotation corresponds to a vector pointing away from the observer and counter-clockwise rotation corresponds to a vector pointing towards the observer.

Units and dimensions

Question	Answer
Scalar or vector?	Vector
MLT dimensions	$T^{-2}$: MLT;0;0;-2
SI units	$rad/s^{2}$ or radians per second squared
other units	degrees per second squared, revolutions per second squared