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Earlier quoted context omitted.
But aren't things like road signs in mph defined by law?
My understanding of speed limits in the US is that each state defines it. There is no national speed limits (hence why Montana is famous for its high speed limits on motorways, but not much else). But I doubt that Washington D.C. uses kph on its speed signs, though.
Earlier quoted context omitted.
One nautical mile is very nearly the length of one minute of arc at the earth's surface.
Wouldn't that make the arc-minute the practical unit?
Yes. However, the earth is not a perfect sphere. The nautical mile is an average arc-minute.
Most of the comments in this thread are talking about the units for personal height, weight, local road signs or for the weather forecast. Those are by far the least important things to be worried about. All of those things are local and there is no carrying cost for them. There would be a cost to change all those signs and forecasts - for no real gain. However, dimensions of physical goods are a constant recurring c…
Good point. In Canada, we still use imperial measures for body height and body weight, and many older folks still talk in miles and fahrenheit. But everyone adjusted to metric for less personal weights and measures, and other abstract measures. Pretty good compromise, I think.
Gym weights, except in Olympic lifting competition, everyone talks lbs.
While in the UK I noticed everyone measures weight in stone (1 stone = 14 lbs).
There's a couple of things you'd want to consider converting to metric: long distances, short distances/dimensions, volumes, weights, and temperature come to mind. Long distances: swap out a bunch of highway signs, consider that 60mph (a mile a minute) ~= 100km/h, not too hard on people but a lot of signage needs to change. Feasible. Volumes: people are used enough to 2-liter bottles of soda, expect the 3.78 liter mi…
>not too hard on people but a lot of signage needs to change. Feasible. Very expensive though. Signs normally have a 20 years expected lifetime. Now you need to replace them all at once. Plus a lot of the sign locations need to be changed, unless you want all those "Exit 29 1 mile" signs to now say "Exit 29 1.6 km".
Exit 14 - 1 Kilometer (.6Miles)
Then, as the old signs wear out, eventually all signs are replaced.
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This is fairly similar to fuel mileage, where some places use miles per gallon (distance per volume) while others use litres per 100km (volume per distance). Changing systems is fairly irrelevant though, since you can still measure your mileage in kilometres per litre if you want.
No, it's different. distance / volume vs volume / distance are just inverses. Weight vs Volume are completely different measures and can only be compared by knowing the specific properties of the contents. Some recipe books have conversion tables for using depending on _what_ you're measuring.
Metrickery is a socialist plot to weaken America. First it's units of measurement divisible by ten, then it's universal health care, then gun control, and finally off to the gulag for the last remaining freethinkers. Sadly, there are people who believe more of less exactly what I just wrote.
It must be fun to live in a world where everyone who disagrees with you is a moron.
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Boat speed is measured in knots. Knots are non-SI, since they're based on the non-SI nautical mile (1 knot = 1nm/hr). But they are a good example of why context is important; the nautical mile is absolutely superior to the kilometer for use in navigation (at sea or in the air). Forcing the SI unit there would actually make the relevant tasks more complex and more difficult.
"the nautical mile is absolutely superior to the kilometer for use in navigation (at sea or in the air)." Why is that?
As Wikipedia puts it:
"In most projections, scale varies with latitude, so on small scale maps, covering large areas and a wide range of latitudes, the linear scale must show the scale for the range of latitudes covered by the map."
"Mariners generally use the nautical mile, which, because a nautical mile is approximately equal to a minute of latitude, can be measured against the latitude scale at the sides of the chart."
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Before we start in... let's remember that in most contexts, the units don't matter. What matters is picking a system and sticking to it. (and that there still is no such thing as a "one size fits all" system of units)
> the units don't matter. What matters is picking a system and sticking to it That is exactly the problem with the imperial system. You have multiple units for the same thing, and when they are multiples of each other, it is in base 12. You could settle on feet and have kilofeet and millifeet, and you'd have a sensible system (apart from being incompatible with the rest of the world).
That's when you're lucky, can also be 3 (yard to feet), 22 (chain to yard), 10 (furlong to chain), 8 (miles to furlong, and that's why a mile is 5280 feet), 5 (gill to fluid ounce), 4 (acres to rod, gallons to quarts), 14 (stones to pounds) and probably everything in-between.
Most of the comments in this thread are talking about the units for personal height, weight, local road signs or for the weather forecast. Those are by far the least important things to be worried about. All of those things are local and there is no carrying cost for them. There would be a cost to change all those signs and forecasts - for no real gain. However, dimensions of physical goods are a constant recurring c…
THe 'sets of tools' argument is kind of spurious. I already have a box full of wrenches; I'd need some more in the box. Nobody argues 'lets get rid of 5/32 bolts, so I can get rid of that wrench'. Its the mental effort to rationalize them that is the real cost. Lets see, slightly larger than 1/4 - is it 7mm? or 8? or 9/32?