An 6-kg mass is attached to a spring hanging from the ceiling and allowed to come to rest. Assume that the spring constant is 40 N/m and the damping constant is 4 N-sec/m. At time t=0, an external force of 2 sin 3t cos 3t is applied to the system. Determine the amplitude and frequency of the steady-state solution.

An 6-kg mass is attached to a spring hanging from the ceiling and allowed to come to rest. Assume that the spring constant is 40 N/m and the damping constant is 4 N-sec/m. At time t=0, an external force of 2 sin 3t cos 3t is applied to the system. Determine the amplitude and frequency of the steady-state solution.