A solid disk rotates in the horizontal plane at an angular velocity of around 0.047 rad/s with respect to an axis perpendicular to the disk at its center. The moment of inertia of disk is around 0.14 kg • m2. From on top, sand is dropped straight down onto this rotating disk, in such a way that a thin uniform ring of sand is made at a distance of 0.40 m from the axis. The sand in the ring consists of a mass of 0.50 kg. After all the sand is in place, determine the angular velocity of the disk?