3.5-m steel beam is lowered by means of two cables unwinding at the
same speed from overhead cranes. As the beam approaches the ground,
the crane operators apply brakes to slow down the unwinding motion.
At the instant considered, the deceleration of the cable attached at A is
4 m/s2, while that of the cable at B is 1.5 m/s2. Determine (a) the
angular acceleration of the beam, (b) the acceleration of Point C.