[EMAIL PROTECTED] wrote:
Stan, Position, speed, acceleration, force, and weight are *not defined* (do not exits) without a "frame of reference" (an origin and coordinates) either specified or implied. This *requirement* exists even in the most simple Classical Mechanics (relative motion (speeds) much less than c), long before Einstein Relativity (speeds approaching c or accelerating frames of reference) come into play.
The relationship (by algebraic translation) of those values from one reference frame to another is referred to as Galilean relativity.
These variable quantities (position, speed, acceleration, force, weight) *must* be defined before units for force and weight (as a force) can be specified. The reverse order; first units, and then quantities is *impossible* however diligent and well intended the effort.
Yes, units are defined, standard values of selected quantities. Other values for those quantities are determined by their ratios to those standard values (units). If I say the length of a board is 3 m I am actually saying that the board, L, is 3 times as long as the standard value of length, which is named "meter". That's what makes the quantity calculus work, allowing me to say L/m = 3 by the simple algebraic procedure of dividing both sides of L = 3 m by m. (In this email L is not written in italics, though it normally would be.)
Jim -- James R. Frysinger 632 Stony Point Mountain Road Doyle, TN 38559-3030 (H) 931.657.3107 (C) 931.212.0267
