on 3/26/2002 6:16 PM, kilopascal at [EMAIL PROTECTED] wrote: > mechanical units form most of the base units for SI.
It's of academic interest only, I suppose, but I disagree with the above. There are seven base units. One is electrical (the ampere), one is thermal (the kelvin), one is chemical (the mole) and one is used in illumination physics (the candela). That's four out of seven. Even if one accepts the suggestion that the other three (m, kg, s) are all "mechanical" (which I don't*), it is not accurate to state that "most" of the base units are mechanical. Three out of seven is not "most". Regards, Bill Hooper college physics teacher (retired), USA (Florida) *P.S. The other three base units are the kilogram, the second and the metre. Are they "mechanical units? The kilogram is just as important in thermal physics and maybe even more important in nuclear physics than it is in mechanical physics, so I don't accept the suggestion that the kilogram is purely a mechancial unit. Many things vary with time, including the electric and magnetic fields in electromagnetic waves (light, radio, etc.), transfer of thermal energy by heat flow, radioactive decay, and others. Therefore, I don't accept the notion that the second is purely a mechanical concept. Although the metre is certainly used in mechanical sense to describe position and velocity, etc. (surely mechanical concepts) it is also used to describe thickness of barriers through which heat, light, sound, ionizing radiation, etc. may or may not pass and other things which are not necessarily "mechanical". So I can't even bring myself to classify the metre as a purely mechanical unit. +-+-+-+-+-+-+-+-+-+-+-+ Do It Easy, Do It Metric! +-+-+-+-+-+-+-+-+-+-+-+
