The angular speed is the angular displacement divided by the time interval (in this Illustration, since there is no acceleration, the average speed and the instantaneous speed are the same). The easie...The angular speed is the angular displacement divided by the time interval (in this Illustration, since there is no acceleration, the average speed and the instantaneous speed are the same). The easiest way to remember the forms for the kinetic energy of rotation and the angular momentum is by analogy with the kinetic energy of translation and the linear momentum.