FUnny there should be a recent “Cecil’s Mailbag” (or whatever they call it now) article about the metric system as I had a question about the metric system myself that i was just about to post.
I was driving down the road hen all of a sudden it hit me - we’re never gonna have the metric system in this country if the road signs continue to read miles per hour. This led me to thinking about the fight for metric system respect in general. How far did the people pushing it really go? WHat was their plan of action? Anybody out there have information about this war for the metric system in average American life? Is the war over?
We have effectively made the very expensive choice to maintain two unit systems, the SI and the US Customary. Technical people pretty much have to use SI units because the Customary ones are too awkward, and nontechnical people resist changing for whatever their reasons. There are hidden costs - like me spending extra hours in my work to translate between systems - and sometimes visible costs - like the occasional space probe getting destroyed.
The units that most people have to do the most work with, those for money, got changed to a base 10 system pretty damn fast in the US, though, didn’t they?
Wait just a minute here - I certainly am, and work with many “technical” people, yet must use English units on a daily basis.
For example - try to find fan performance curves for power plant fans in anything but “acfm”, “hp”, and “in w.g.”. Try to buy coal in the US in anything but “Btu/lbm” or “cents/MBtu”. Or measure unit heat rate in anything other than “Btu/kW*hr” (a true bastardization of English and SI units indeed, heat rate).
Try to buy or measure pump performance in anything other than feet of head or gpm of flow…you get the picture. Many, many technical people use these units, awkward though they may seem.
You know those big green freeway signs that show the distance to the next 3 big towns? Well, here in California, I’ve seen some of them list the distances in both miles and kilometers.
That’s the extent of California’s “metric conversion” effort, though. Speed limit/maximum speed signs are still only in miles per hour, and distance-to-the-next-exit signs are still only in miles (rounded to the nearest 1/4 mile).
How hard have you tried? I wouldn’t be able to make sense of btu/kWh without an elaborate series of conversions to get back to MJ/kWh, and gallons per minute means nothing to me. It really is possible to do all these things in metric and lots of people do. In fact I have a sneaking admiration for anyone who can work in non-natural units and get the right answers!
Chas.E, if the King’s Henry needed to be 1m long, I could direct him to the many people who keep posting to my hotmail a/c offering just such a service. Sorry.
Being more serious, heat rate is a dimensionless quantity, and the only reason we use units for it at all is because electricity is sold by the kWh and fuel is not (GJ, therms, Mbtu…). When it comes down to it, if we were serious about SI we would scrap kWh altogether and measure electricity in joules, but it’s not a very practical unit.
Honestly i think the metric system is much easier. The number of ounces in a pound is different then the number pints in a gallon if I remember correctly. On the other hand… there are 100 centimeters in a meter, 100 centigrams in a gram, ect. I know how many meters are in a kilometer… but god help me if someone asks how many feet are in a mile. Chemistry taught met he metric system and I’m thankful for it. It’s not that difficult after all.
You are not getting my point. My point is that the units are traditional, and in the US vendors, manufacturers, consultants, engineers, plant managers, plant operators, maintenance personnel, performance engineers, coal buyers, etc. all use these units. They are inefficient and unwieldy. I know this already. Just like I know heat rate is dimensionless - I just presented a paper on Heat Rate improvement, I know a little about it.
My point was - there are plenty of “technical” people who use these awkward, non-SI units every day. And, I hazard, will continue to use them for decades to come.
I know you know. In fact, my second post about heat rate was by way of conceding that the units we use to measure it are arbitrary and are determined by the environment we work in. I never doubted for a minute you are competent to work in SI and spelll sulphur with a “p” when the need arises.
Chas.E, I got the joke, and just thought your typing error added an extra level of humour.
There was a “dualie” on I40 between Raleigh-Durham Airport and Research Triangle Park when I first arrived here in 1988. They took down the metric part a few years ago (it was kinda kludged onto the back and side).
Am I the only one who doesn’t think US units are awkward? 12 inches in a foot, 5280 feet in a mile, 128 ounces in a gallon… it’s easy if you use it enough. Sure, it’s cute that 1 cm^2 of water weighs one gram, but a pint’s a pound the whole world 'round.
Surprisingly enough, it isn’t. Over here, a pint is 20 fl oz., and the rhyming couplet goes: “A pint of clear water weighs a pound and a quarter.” Same goes for tons, ounces, horsepower and miles: the words do not have the same meaning for everyone, whereas “a meter’s a meter the whole world 'round”.
A couple of mixed-metric tales I’ve been involved in.
I was once a reviewer for a technical journal related to helicopters. The standards for the publication ostensibly required everything to be in SI units, but this was usually ignored. I reviewed a paper in which the author used “g’s” as a unit of vibratory acceleration (quite common). I remarked to the author and editor that the proper SI unit for acceleration should be m/s^2. I was not suprised that I was ignored. It did, however, lead to a lively discussion on whether a “g” is a metric unit.
In another case, I was involved in writing a specification that, up front, insisted that the contractor prepare a proposal in SI units. Then we went on to talk about missions that were to be flown at an airspeed of so-many knots, for distances of so-many kilometers, at a gross weight of so-many pounds, at an altitude of so-many feet.
General units (the bastard system) need to stop being taught in schools. Focus on real units (SI) and as a side note mention they can be converted to these silly things by using factors that can be found in the textbook. People need to just switch over. When all my chem labs needed to have the temp in metric, I swapped my normal weather reporting to metric too. Now, I open my yahoo weather page and get the highs and lows (6, -4…going to be a wee chilly) and when someone says forty degrees my jaw drops.
Teach it and use it, when people have to do running calculations to understand signs, the signs will change. (Hopefully the signs will change sooner, actually)
I was horrified that my Statics professor actually makes us do engineering in English units. (lbf vs lbw anyone?) I usually convert everything to SI, do the problem, and then convert it back, just to be a prick.
