Gene Mechtly wrote in USMA 16100: >On Tue, 6 Nov 2001, Joseph B. Reid wrote: >> >> ... torque is usually expressed in newton-metres, > >No. Torque is *defined* as the summation of vector (cross) products of >radius vectors and respective forces at the points of application, only in >the order r and f. > >> This is misleading since a newton-metre is also a joule, which is not a >> torque. > >Torque is a vector quantity, not a unit, neither N.m nor J. The error is >your oversimplification of the definition of torque. > >> I prefer to express torque in joules per radian. > >Not acceptable. Here, again, you ignore the vector properties of torque. > >Gene.
How can one denote the distinction between a newton metre as the unit to meassure energy and the newton metre as the unit to measure torque? How, in Gene's notation, does one distinguish between N.m as a scalar and N,m as a vector? How would Gene distinguish between the unit for measuring radiant power from the unit for radiant intensity, or how does he distinguish the difference between the units for liminous flux and luminous intensity? We evidently need a way to denote whether a quanity is a scaolar or a vector quantity. The radian and steradian offer a way of doing this. Joseph B.Reid 17 Glebe Road West Toronto M5P 1C8 TEL. 416-486-6071
