Confusing Units
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From: F/32 Eurydice on 2 Mar 2010 10:50 I just learned how to convert units involving acres and hectares, and I've half learned to convert nautical mile to terrestrial miles. This took me even longer than learning to convert esu (stat-coulombs) to Coulombs. I'm still a little uncertain about emu, but I'm pretty sure they're the same as esu, since B & E have the same units when you set epsilon_0 and mu_0 to 1.
From: jbriggs444 on 2 Mar 2010 12:31 On Mar 2, 10:50 am, "F/32 Eurydice" <f32euryd...(a)sbcglobal.net> wrote: > I just learned how to convert units involving acres and hectares, and > I've half learned to convert nautical mile to terrestrial miles. This > took me even longer than learning to convert esu (stat-coulombs) to > Coulombs. I'm still a little uncertain about emu, but I'm pretty sure > they're the same as esu, since B & E have the same units when you set > epsilon_0 and mu_0 to 1. With miles, the distinction is between the "nautical mile" and what is sometimes referred to as the "statute mile" or "international mile". The former is nominally 1 minute of arc on the Earth's surface as measured at the equator. The formal standard is 1852 meters exactly. The latter is both nominally and formally 5280 feet = 1609.344 meters exactly. There is also the "U.S. survey mile" which uses an older conversion factor and thus differs slightly from the statute mile. [It's one thing to change the standard of length by which lumber and textiles are sold. It's a different thing to go back into public records and change all the plats on all the deeds]
From: Frank on 2 Mar 2010 13:12 On 3/2/2010 12:31 PM, jbriggs444 wrote: > On Mar 2, 10:50 am, "F/32 Eurydice"<f32euryd...(a)sbcglobal.net> wrote: >> I just learned how to convert units involving acres and hectares, and >> I've half learned to convert nautical mile to terrestrial miles. This >> took me even longer than learning to convert esu (stat-coulombs) to >> Coulombs. I'm still a little uncertain about emu, but I'm pretty sure >> they're the same as esu, since B& E have the same units when you set >> epsilon_0 and mu_0 to 1. > > With miles, the distinction is between the "nautical mile" and what is > sometimes referred to as the "statute mile" or "international mile". > > The former is nominally 1 minute of arc on the Earth's surface as > measured at the equator. The formal standard is 1852 meters exactly. > > The latter is both nominally and formally 5280 feet = 1609.344 meters > exactly. > > There is also the "U.S. survey mile" which uses an older conversion > factor and thus differs slightly from the statute mile. [It's one > thing to change the standard of length by which lumber and textiles > are sold. It's a different thing to go back into public records and > change all the plats on all the deeds] > Reading "Chung Kuo". I came across the li. See they have gone to SI but this is interesting: http://en.wikipedia.org/wiki/Chinese_units_of_measurement Also reminded, years ago, working summer job of toll collector, when people asked me how far it was to the race track, I'd tell them in furlongs ;)
From: Uncle Al on 2 Mar 2010 15:13
F/32 Eurydice wrote: > > I just learned how to convert units involving acres and hectares, and > I've half learned to convert nautical mile to terrestrial miles. Oh wow - a Community College PhD/Enuresis > This > took me even longer than learning to convert esu (stat-coulombs) to > Coulombs. I'm still a little uncertain about emu, but I'm pretty sure > they're the same as esu, since B & E have the same units when you set > epsilon_0 and mu_0 to 1. -- Uncle Al http://www.mazepath.com/uncleal/ (Toxic URL! Unsafe for children and most mammals) http://www.mazepath.com/uncleal/qz4.htm |