A 500-lb flywheel is at rest when a constant 200 lb ⋅ ft couple is applied. After executing 750 revolutions, the flywheel reaches its rated speed of 3000 rpm and the couple is removed. Assuming that the kinetic friction results in a constant couple of magnitude 12.5 lb ⋅ ft, determine

(a) The radius of gyration of the flywheel,

(b) The number of revolutions that the flywheel executes after the couple is removed and before it comes to rest.