The concrete block weighing \(644 \mathrm{lb}\) is elevated by the hoisting mechanism shown, where the cables are securely wrapped around the respective drums. The drums, which are fastened together and turn as a single unit about their mass center at \(O\), have a combined weight of \(322 \mathrm{lb}\) and a radius of gyration about \(O\) of \(18 \mathrm{in}\). If a constant tension \(P=400 \mathrm{lb}\) is maintained by the power unit at \(A\), determine the vertical acceleration of the block and the resultant force on the bearing at \(O\).

W = 322 lb ko=18" 24" 12" P = 400 lb 644 lb 45 A