Part I gave you the everyday formulas. This is the one you open when you're actually sizing something — a motor, a cable, a heater — or working a process number. Same live-calculator idea: motor & servo sizing (accel torque, RMS, the inertia-ratio rule), electrical sizing (voltage drop, transformer, PF-correction caps, breakers), process/flow/heat, and a live unit converter for the conversions you redo forever.