thats funny you should pull up an article from my good buddy Rick Armstrong of Kollmorgen! We go back to the days when this inertia stuff was just getting figured out! Rick and I worked together for 20+ years, and at the same time on the programs to do motor sizing and had long sometimes heated discussions on the theory! I am honored to call Rick my friend! He retired last year from Kollmorgen. Motioneering is his baby (although I like to think some of the original equations are mine!)