- Angular acceleration
Angular acceleration is the rate of change of
angular velocityover time. In SIunits, it is measured in radians per secondsquared (rad/s2), and is usually denoted by the Greek letter alpha ().
The angular acceleration can be defined as either:
: , or
where is the angular velocity, is the linear tangential
acceleration, and r is the radius of curvature.
Equations of motion
For rotational motion, can be adapted to describe the relation between
torqueand angular acceleration:
: ,where is the total torque exerted on the body, and is the mass
moment of inertiaof the body.
For all constant values of the torque, , of an object, the angular acceleration will also be constant. For this special case of constant angular acceleration, the above equation will produce a definitive, constant value for the angular acceleration:
For any non-constant torque, the angular acceleration of an object will change with time. The equation becomes a differential equation instead of a constant value. This
differential equationis known as the equation of motion of the system and can completely describe the motion of the object.
Wikimedia Foundation. 2010.