  We continue to consider the question of what language features are needed to
effectively model cyber-physical systems (CPS). In previous work, we proposed
using a core language as a way to study this question, and showed how several
basic aspects of CPS can be modeled clearly in a language with a small set of
constructs. This paper reports on the result of our analysis of two, more
complex, case studies from the domain of rigid body dynamics. The first one, a
quadcopter, illustrates that previously proposed core language can support
larger, more interesting systems than previously shown. The second one, a
serial robot, provides a concrete example of why we should add language support
for static partial derivatives, namely that it would significantly improve the
way models of rigid body dynamics can be expressed.
