Just posted, and yes, that is the name used on the list by the gent to whom I'm responding:
Glad to see you have a sense of humor, OldFart. (grin) Dave's pretty close to the mark about the SI and the light year. The seven base (not basic) units are the meter, kilogram (not gram), second, ampere, kelvin, mole, and candela. With those seven base units and their derived units you can measure just about everything but true love. As Dave said, there are 22 specially name derived units and some which have no special name (such as m/s). Actually, most people need to know fewer than a dozen of these. You already know and use some of them, such as the second. The volt, ampere, and watt come to us from 19th century studies of electricity and magnetism, in which U.S. scientists played a big role. There are also some non-SI units that are allowed for use with the SI, such as the minute (min), hour (h, not hr), and day (d). But the week, month, and year are out. The month and year each come in several different sizes so that makes sense. The meter, kilogram, and degree Celsius are about all you need to know along with the ones just mentioned. If you want, you can throw in the liter which is just a special name for 1 dm3, or a cube 10 cm on an edge. That beats trying to learn the more than 2000 non-SI units that Americans have used in the past! Here are some handy metric thumb rules for you. The Earth is 150 Gm from the Sun and 1 Gm = 1 000 000 km. The Earth's circumference is 40 000 km. The Earth travels at 30 km/s around the Sun and the Moon travels at 1 km/s around the Earth. Most "shooting stars" are traveling at 40 to 60 km/s when they hit our atmosphere to cause that quick streak of light. And light travels through spacd at 300 Mm/s or 300 000 km/s. The nice thing about all of this is that I used only two units, the meter and the second. All the rest was dealt with with prefixes, which do the same thing to any other unit they are attached to. No new unit names are needed when going from small to big sizes, as are needed with our series inch, foot, yard, fathom, pole, furlong, mile, and league; the meter and the standard prefixes handle all that and more. Jim -- James R. Frysinger University/College of Charleston 10 Captiva Row Dept. of Physics and Astronomy Charleston, SC 29407 66 George Street 843.225.0805 Charleston, SC 29424 http://www.cofc.edu/~frysingj [EMAIL PROTECTED] Cert. Adv. Metrication Specialist 843.953.7644
