A 1.0- kg mass is attached to a string wrapped around a shaft of negligible mass and having a 7.0- cm radius. A dumbbell-shaped "flywheel" made from two 0.500- kg masses is attached to one end of the shaft and perpendicular to its axis (see the figure). The mass is released from rest and allowed to fall 1.2 m to the floor. It reaches a speed of 2.4449 m/s just before striking the floor. How far apart are the masses of the dumbbell?