Why the U.S. doesn't use the metric system

One theory at least :lol:

I was teaching when “metrification” was the rage. The problem was everyone wanted to know what the equivalent was. I ,being the chemist, was teaching and saying, “No, just learn the unit. forget equivalents.”

Well the mentality never caught on, so even when soft drink companies came on with liter bottles of their swill, and people knew what a liter of it was, still the US mentality never caught on.

Considering who were the teens at the time, including some rich guy now, who has said he is in favor of global warming as it might bring relief to Iowa and parts around here.

Probably the reason it took the UK so long to go metric, in some things at least, was that it was invented by the French, and you know how well we got on with them over the past few hundred years (or not) :wink:

Stuart

Many years, nay decades, ago, I was told that there were only two countries in the world that did not use international paper sizes (e.g. A0-A8 for printing and writing, B… series for envelopes etc.), North Yemen (yes, it existed then!) and the USA. Now there is only one!

I think teaching must have been even worse for physicists: I had to learn two metric systems (CGS and MKS) at school and later had to get used to the SI system. “[Since 1960] the SI has been adopted by all developed countries except the United States.”

Still selling beer in pints here, though. (Imperial pints, that is!)

That MKS to CGS (or was it the other way?) shift sounds simple, but then you get to switching units like newtons and dynes and suddenly is isn’t so simple 8O

I never really figured out what a mole is :oops:

CGS to MKS was relatively simple for things like force and energy (move the decimal point), but electrostatic/electromagnetic stuff was a minefield.

Suppose mole might have been easier to understand for chemists?

Quite possibly wrong, as I’m drawing on brain cells some 55 or so years old…

I think a mole is the molecular weight, in grams, of the chemical, dissolved in one litre of water…

(Thanks Mr Munro)

Ken

Yeah, that’s a molar solution all right!

I stopped looking at SI unit definitions in the '70s - it was too depressing - but the mole used to be defined as “the amount of substance which contains as many elementary entities as there are atoms in 0.012 kg of carbon 12”. Then you had to specify what the elementary entities were. . .

Niko, I’m with you!

Exactly!

"The unit is defined as the amount or sample of a chemical substance that contains as many constitutive particles, e.g., atoms, molecules, ions, electrons, or photons, as there are atoms in 12 grams of carbon-12 (12C), the isotope of carbon with standard atomic weight 12 by definition. This number is expressed by the Avogadro constant, which has a value of approximately 6.022140857

A man after my own heart, the firkin (9 gallons) being a quarter of that well-known Imperial measure, the barrel [e.g. of beer]! An easier concept to grasp, by far, than the mole.

Discussion on metric usage ???

I wouldn’t touch that with a 3.048 meter pole !

You’re trying to compare apples with steel bolts there. A firkin is a measurement of volume whereas a mole is a quantity of something, e.g. atoms, molecules, peanuts, etc. So you might say that you have a cubic metre of shelled peanuts or you might say you have 641,000 (approx) peanuts, but you can’t convert between the two unless you know something about the specific items held within the volume, e.g. the approximate volume of a peanut and the packing structure of peanuts.

For those interested there are approximately 1*10^-21 moles of shelled peanuts in a cubic metre. I haven’t done the equivalent calculation for molecules of ethanol in beer…we’d need to know what strength of beer you were drinking first.

Oh…before I forget…a very Happy New Year to everyone…including those who are metrically challenged but still like to drink beer!

No, I think I was just agreeing with niko that the definition of the mole doesn’t immediately make the heart beat faster for its economy of language and conceptual beauty. . .

Happy New Year!

The definition of our favourite Imperial units isn’t really much better. For example an International Foot is defined as 0.3048 of a metre. A metre is defined as
the distance light travels, in a vacuum, in 1/299,792,458 seconds with time measured by a caesium-133 atomic clock.

So the definition of a foot, i.e. ‘the distance light travels, in a vacuum, in 0.3048/299,792,458 seconds with time measured by a caesium-133 atomic clock’ doesn’t really hit the top spot in the poetry charts :wink:

But that’s the new definition, when I went to school a metre was equal to 1.650,763.73 wavelengths of the orange-red emission line in the electromagnetic spectrum of the krypton-86 atom in a vacuum :lol:

I never knew there was such a thing. . . Imperial yes, but International?

Bring back the ell or the clothyard!