Damped forced vibration yb=tan 25w/wn (wn)2 =0 =0.2 C=0.5 0.1 0 Fo sint Xsin(wt-al Fo A wt tDamped Forced Vibration ψ = tan−1 " 2ζω/ωn 1 − (ω/ωn) 2 # 0 1 2 3 7