These three equations must be written for each moving body in the system which
will lead to a set of linear simultaneous equations for any system. The set of simultaneous
equations can most conveniently be solved by a matrix method as was shown in
Chapter 5. These equations do not account for the gravitational force (weight) on a link.
If the kinematic accelerations are large compared to gravity, which is often the case, then
the weight forces can be ignored in the dynamic analysis. If the machine members are
very massive or moving slowly with small kinematic accelerations, or both, the weight
of the members may need to be included in the analysis. The weight can be treated as an
external force acting on the CG of the member at a constant angle.