In this video I will explain the acceleration vector (a(t)=dv(t)/dt) given the general equation of the position vector v(t)=Rcos(t)i+Rsin(t)j. Acceleration vector, a(t), is also know as the centripetal acceleration as it represents the change in the direction of the velocity vector (not the change in the magnitude). Also note that both |v(t)|=R and |a(t)|=R.