Angular velocity

In physics, the angular velocity is
defined as the rate of change of
angular displacement and is a vector
quantity (more precisely, a
pseudovector ) which specifies the
angular speed ( rotational speed ) of an
object and the axis about which the
object is rotating. The SI unit of
angular velocity is radians per second,
although it may be measured in other
units such as degrees per second,
degrees per hour, etc. Angular
velocity is usually represented by the
symbol omega (ω, rarely Ω).
The direction of the angular velocity
vector is perpendicular to the plane of
rotation, in a direction which is
usually specified by the right-hand
rule . [1]