Hi I was reading through the following report that I found on the web, in it is an equation I am very unclear on. Its equation 1, page 5. I think that equation relates to ma = F(left) + F(right) - mg as it describes body height. So I was wondering why on the LHS of the equation it has a + 2/m (Cl + Cr)v + 2/m (kl + kr)z? I replaced the z's wit their equivalents i.e z = x z dot = v z dot dot = a Could anyone take the time to look at the diagram (in the tables page shown at the end) and explain that part to me?