A single-degree-of-freedom system has a mass of 3 kg, spring stiffness of 240 N/m and viscous damping of 18 N-s/m. Give: a) System differential equation b) Damping condition (underdamped, overdamped, or critically damped) c) find the displacement as a function of time for initial conditions: x(0) = 10 mm and x(0)= 0.1 m/sec.