0000,0000,0000> Sean ... it's worse than that ... since ne ither the joule not the > coulomb are among the seven SI based units, this is how they do it: > V = (m^2)(kg)(s^-3)(A^-1) > > So we "should" say, "a 5(m^2)(kg)(s^-3)(A^-1) battery", NO NO NO! NOBODY is saying we shouldn't use the derived units of the SI. That is NOT what NIST says! The Volt is an accepted derived unit. So is a Farad. You are encouraged not to use the cgs system and some other traditional sets of derived units in favor of the standard units, either derived or base units. For many types of problems, if you need to manipulate quantities that are in the standard units, the fact that they are defined in terms of the base units (no multipliers) actually helps. For example, one Pascal applied to a 1 m^2 area applies a total force of 1 Newton. However, the reason that people won't give up all the odd unit systems is because of what Sean pointed out: That the units come out even for certain types of problems. But is easy for him to take the answer he gets in cgs, and convert to standard mks, at least they are metric. Try that in nautical miles, lbs force, and seconds. you have to be a rocket scientist to get the conversions right. Sometimes even THEY don't. < -Barry.