IMPORTANT PLEASE SOLVE USING ANGULAR VELOCITY OF

AB $3$ rad$/$s$^2($CLOCKWISE$)$

$16\mathrm{.}123$ End $A$ of the $8-kg$ uniform rodAB is attached to a collar that can slide without friction on a vertical rod. End $B$ of the rod is attached to a vertical cable $BC.$ If the rod is released from rest in the position shown, determine immediately after release $(a)$ the angular acceleration of the rod, $(b)$ the reaction at $A.$