Generalized Momentum Force

We have

$$\begin{array}{rl}\dot{q}& =W^{-1}(q)p\\ \dot{p}& =\frac{\partial L}{\partial q}+Q\end{array}$$

Where $p=W(q)\dot{q}$ (mass times velocity) is the generalized momentum, and $Q$ is the Generalized Forces.