Under this section we're going to go back and revisit the concept of modeling only now we're going to look at this in light of the fact as we now understand how to solve systems of differential equations.

We're not really going to be solving any differential equations for this section. In its place we'll just be setting up a couple of problems which are extensions of several of the work that we've done in previous modeling sections whether this is the first order modeling or the  vibrations work we did in the second order chapter. Approximately all of the systems which we'll be setting up now will be nonhomogeneous systems are that we only briefly looked at, will be nonlinear is that we didn't look at and/or will include systems with more than two differential equations are that we didn't look at, even though most of what we do know will still be true.