Physics
The speed of rotation is given by the angular frequency (rad/s) or frequency (turns/s, turns/min), or period (seconds, days, etc.). The time-rate of change of angular frequency is angular acceleration (rad/s²), This change is caused by torque. The ratio of the two (how heavy is it to start, stop, or otherwise change rotation) is given by the moment of inertia.
The angular velocity vector also describes the direction of the axis of rotation. Similarly the torque is a vector.
According to the right-hand rule, the direction away from the observer is associated with clockwise rotation and the direction towards the observer with counterclockwise rotation, like a screw.
See also: Speed#Tangential Speed, rotational energy, angular velocity, Centrifugal force (fictitious), centripetal force, circular motion, circular orbit, Coriolis effect, spin (physics), rotational spectroscopy, and Rigid body dynamics#Rigid body angular momentumRead more about this topic: Rotation
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