(by hand) label the displacement (or rotation) coordinate and derive the equation of motion (eom) for the sdf systems (a) through (e). express the stiffness component (k or ke) in terms of the variables given, e.g. a, e, l, r, etc. if not explicitly stated otherwise, assume these are real systems that have viscous damping. for all systems, draw the fundamental mass-spring-damper model with the components that apply.