The diagram above shows the velocity vector of a particle in uniform circular motion at two instants of time. By vector addition we can see that the change in velocity, Δv , points toward the center of the circle. Since acceleration is the change in velocity over a given period of time, the consequent acceleration points in the same direction. Thus we define centripetal acceleration as an acceleration towards the center of a circular path. All objects in uniform circular motion must experience some form of uniform centripetal acceleration.