A uniform disk with mass 100 kg and radius 1.0 m is spinning like a merry-go-round about a vertical axis through its center and perpendicular to the plane of the disk. It rotates at an initial angular speed of rad/s. A 40 kg mass of putty drops from above and lands on a point 0.50 m from the center from the disk and sticks to the disk. What is the final angular speed of the disk-putty system, in rad/s?