Since we are using a force-wave simulation, the state variable (delay element output) is in units of physical force (newtons). Specifically, . (The physical force is, of course, 0, while its traveling-wave components are not 0 unless the mass is at rest.) Using the fundamental relations relating traveling force and velocity waves
where here, it is easy to convert the state variable to other physical units, as we now demonstrate.
The velocity of the mass, for example, is given by
The kinetic energy of the mass is given by
A More Formal Derivation of the Wave Digital Force-Driven Mass
Series Reflection Free Port