Posted by **Emily** on Friday, November 18, 2011 at 8:32am.

Two disks are mounted (like a merry-go-round) on low-friction bearings on the same axle and can be brought together so that they couple and rotate as one unit. The first disk, with rotational inertia 2.58 kg·m2 about its central axis, is set spinning counterclockwise (which may be taken as the positive direction) at 289 rev/min. The second disk, with rotational inertia 5.78 kg·m2 about its central axis, is set spinning counterclockwise at 933 rev/min. They then couple together. (a) What is their angular speed (rev/min) after coupling? (b) If instead the second disk is set spinning clockwise at 933 rev/min, what is their angular velocity (in rev/min, using the correct sign for direction) after they couple together?