The block of weight W = 100 lb is suspended by two springs each of stiffness k = 200 lb/ft and is acted upon by the force F = 75 cos 15t lb where t is the time in seconds. Determine the amplitude X of the steady-state motion if the viscous damping coeffi- cient c is (a) 0 and (b) 60 lb-sec/ft Compare these amplitudes to the static spring deflection δst.