Total Energy = Potential Energy at the top of the board = Translational Energy (m*v*v/2) + Rotational Energy (I*w*w/2). Since the hoop has an I value of M*R*R and the wooden disk is half that, the hoop will only have 3/4 of the velocity of the disk at a particular height. By the equation V2=V2o+2a(x-xo), the distance the hoop travels by a particular time will be the square root of 3/4 times the distance travelled by the disk.