Centripetal acceleration is the acceleration experienced by an object moving in uniform circular motion, resulting from a net external force. The direction of centripetal acceleration is always towards the center of the circle. The magnitude of centripetal acceleration can be calculated using the formula ac = v^2/r, where v is the linear or tangential speed of the object and r is the radius of the circle. Alternatively, it can be expressed in terms of angular velocity as ac = rω^2, where ω is the angular velocity of the object. The unit of centripetal acceleration is meters per second squared (m/s^2) . It is important to note that centripetal acceleration does not change the speed of circular motion, but only its direction.