Hello again, Yesterday, through your help, I took my understanding to a new level. I can now phrase my single question and I hope you will allow me to make it a separate thread... I understand that the integrand in a line integral is a natural 1-form. I understand that to obtain WORK = F.dx that Force is thus a 1-form. (In fact, I understand that velocity and acceleration are vectors but force and moments are 1-forms.) BUT WHY IS FORCE A 1-FORM, PHYSICALLY? I understand the outcome of the MATH, but what is the physical meaning of Force (acceleration weighted with mass) being a 1-form?