Spring-Mass (Parallel) Impedance Diagram

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