Mass-Spring-Wall (Series) Impedance Diagram

$$\begin{eqnarray*} F_{\mbox{ext}}(s) &=& F_m(s) \; + \; F_k(s)\\ [5pt] V_{\mbox{e... ...\frac{F_{\mbox{ext}}}{V_{\mbox{ext}}}{} \; = \; ms + \frac{k}{s} \end{eqnarray*}$$