A string is wound around a uniform disc of radius 0.65 m and mass of 2.2 kg. The disc is released from rest with the string vertical and its top end tied to a fixed support. Calculate the speed of the center of mass when, after starting from rest, the center of the mass has fallen 3 m. The accleration of gravity is 9.8 m/s^2. Answer in units of m/s.