Determine the magnification factor of the block, spring, and dashpot combination in Prob. 22–65.

Prob. 22–65..

A 7-lb block is suspended from a spring having a stiffness of k = 75 lb/ft. The support to which the spring is attached is given simple harmonic motion which may be expressed as δ = (0.15 sin 2t) ft, where t is in seconds. If the damping factor is c/c_c = 0.8, determine the phase angle ϕ of steady- state vibration.