Uniform circular motion
In motion on a circle. The period, T, is the time take for one complete revolution and the distance covered is the circumference 2(pi)r. Therefore, v = 2(pi)r/T. Constant speed, yet accelerating ... how can that be true? Centripetal acceleration (center seeking), ac = v^{2} /r Centripetal Force is in the same direction as the acceleration ... toward the center. This is a description of the direction of a force created by uniform circular motion.
Angular velocity, w = (change in angle)/(change in time). Linear velocity, v = r(w) Angular acceleration, alpha = (change in w)/(change in t) Linear acceleration, a = r(alpha) 
