5.2 A system with $m = 0.010 \, kg$, $s = 36 \, N \, m^{-1}$ and $b = 0.50 \, kg \, s^{-1}$ is driven by a harmonically varying force of amplitude 3.6 N. Find the amplitude A and the phase constant $\phi$ of the steady-state motion when the angular frequency is (a) $8.0 \, s^{-1}$, (b) $80 \, s^{-1}$, and (c) $800 \, s^{-1}$.