The 30-lb block is attached to two springs having a stiffness of 10 lb/ft. A periodic forc...

The 30-lb block is attached to two springs having a stiffness of 10 lb/ft. A periodic force F = (8 cos 3t) lb, where t is in seconds, is applied to the block. Determine the maximum speed of the block after frictional forces cause the free vibrations to dampen out.