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October 11, 2012

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Well, a fifth of a gallon is pretty close to 750 ml. Hmmm... why do I know that?

So, yeah, a litre is more like a quart. Ride a bike.

If you take a fifth, dividing by zero is easy.

Gas is still comparatively cheap compared to when most of us were kids, when you add in fuel efficiency.

http://www1.eere.energy.gov/vehiclesandfuels/facts/2012_fotw741.html

What year was that brown station wagon, and how big was the engine?

Anybody watch the debate? The Balloon Juice crowd seems to feel pretty good about how it went for Biden, so maybe I would have enjoyed it.

Biden made cleek proud.

I thought Biden did well, but Ryan responded well. I don't know who's still up for grabs or why they are, but I think Biden might have gained a slight edge among these inexplicable people, but no more than a slight one.

I found Biden a bit more credible, but I can't say how much that's a matter of my own (perfectly justified) biases (for the guy with way better policy preferences).

It wasn't so much that Biden won (although I think that he did). It was that he really needed to give a good enough performance to re-energize the Democrats' base. And he definitely did more than well enough for that.

From the way things look so far, turnout is going to make the difference. And the Democrats have shown that they have the better ground game in the places where it counts -- if they can just motivate their troops to turn out and work. This effort did that.

Hairshirt, 1976 pontiac grand safari, 9 seatbelts, 476 CU IN, 4 barrel carb, 4 decibel fm radio. Loved that car. Wish I Still drove it.

http://upload.wikimedia.org/wikipedia/commons/5/5a/1972_Pontiac_Grand_Safari.jpg

Almost like that. But not quite, and definitely not a Subaru.

Pretty sure we had 18 people in it at least once, not including morelynview.

lj,

Unit conversions are always a trap for the unwary. So don't feel too bad about not knowing that a liter is basically a quart.

Wonkish aside here: I currently work on a project where Europeans, Americans, and Japanese are simultaneously trying to work to mutual specs on things like pressure. Americans like measuring pressure in psi, metric folk in kilopascals. It's easy to divide the wrong way, or slip a decimal point, or something, when translating a pressure number in a memo to the opposite tribe. So I always make sure to say it in "atmospheres". If the pressure I mean to specify is 1.47psi, I call it "0.1 atm" in parentheses. Native users of kilopascals, who know by heart how many kilopascals to the atmosphere, stand a better chance of catching any error I might have made in my unit conversions.

The point of the wonkish aside is: units are arbitrary, but physical constants are real things, so it's ratios (e.g. fractions of 1 atm) that minimize confusion.

Now to circle back: money is usually expressed in arbitrary units like yen or USD, the way pressure is usually expressed in arbitrary units like psi or KPa. Converting from one arbitrary unit to another is useful, in a way, but it's even more useful to use ratios to physical constants. One useful physical constant is "a day". Remembering that time=money, it's useful to express the cost of gasoline, say, in terms of a day's wages. What fraction of a day's wages does the average Japanese pay for a gallon of gas? And what is the fraction the average American pays?

Actually, to get arbitrary units out of the calculation altogether, I'd put the question this way: what fraction (or multiple) of a day's wages does the average Japanese pay for the gas to drive a Camry from Tokyo to Osaka? what fraction (or multiple) of his wages does the average American pay to drive a Camry from New York to Chicago?

I mean, if somebody told me that gasoline costs fifty zlotys per hogshead in Freedonia, I could look up the conversion of zlotys to dollars and hogsheads to gallons and do the arithmetic. But would it tell me whether gas is "more expensive" or "cheaper" in Freedonia than in the US? Yes, if I was working up a budget, in dollars, for a road trip through Freedonia. No, if the question was: who can better afford to drive a given distance -- a Freedonian or an American?

--TP

I watched the debate. Biden was good. Ryan was a prevaricating putz. But you can't go by me; I'm the guy who keeps pointing out that "small businesses" DO NOT PAY TAXES.

I'll admit I've been using the ¥100/$1 conversion for close to 19 years now, since my time living in Japan. Having said that, I'd never mistake a liter for a half gallon (I just figure it's about a quart), so at least my quick and dirty price would be $5.80/gallon.

Now, when I lived in Japan I didn't have a car (despite my working for a car company lol), so I was completely indifferent to the price of gas. I figured a car was a silly extravagance for a single guy. Trains, subways, and buses got me anywhere I wanted to go, and I didn't have to pay the obscene Japanese prices for parking anyplace other than my apartment or work. Now, if I had a spouse and a couple of kids I might feel differently, when faced with having to buy four tickets anytime we wanted to go someplace.

Tony,

actually, we European engineers don't use the "atmosphere". That is extremely inconvenient 101.325 kPa. For mechanical engineers, a suitable unit is the non-SI "bar", which is 1E5 Pa.

And the unit system is not quite as arbitrary as you claim. The basis is arbitrary, but the SI forms a single, logical whole where the units relate to each other in a non-arbitrary way. This stands in stark contrast to the imperial system, where you have a terrible amount of ad hoc -units.

Lurker,

I absolutely agree about the SI. I especially like the fact that 1 Joule is both 1 Newton*meter and 1 watt*second. It is unfortunate that nature gives us constants which are almost, but not exactly, round numbers in SI. Gravity is 9.8, not 10; atmosphere is 1.013, not 1; the speed of light is not quite 300,000; and so on. The guys who set up the metric system in the first place could have given God some good advice, I think :)

--TP

I'm partial to the electron volt, myself. It's just a cool unit, conceptually.

jrudkis,

I figured you were going to come back with something about my 1968 Mercury Marquis. I estimate that car's mileage to have been around 8 MPG, with a light tail wind and going slightly downhill. I was just lucky that regular gas (i.e. not unleaded) had dipped fairly well below a dollar per gallon when I was driving that beast to school.

Joe Biden for Pres!

I'm the guy who keeps pointing out that "small businesses" DO NOT PAY TAXES.

oh yeah. makes me fume when they start in with that, too.

i do like the Dems' new talking point that the def'n of "small business" includes many of the super-rich along with many businesses that don't really make much at all. anything to make people go "wait, what?" is a good thing.

and raising the taxes on millionaires ain't gonna do a damned thing to my small business.

If I remember correctly, that 3% stat was something Mitch McConnell was throwing around a while ago, when Obama first proposed extending the Bush tax cuts only for people making less than $250k per year. What I also remember was that the 3% was actually the percentage of returns reporting business income as personal income that would be affected. So the return of someone who has a piece of some business, even if it provided a small percentage of their total income, that total income being greater than $250k, would count as a "small business" being subject to a tax increase.

And even if you were the sole proprietor of a "small" business, are you really going to fire people, or not hire people, because of an increase of less than 4 cents on the dollar only on those dollars of taxable income over $250k? I mean, some business owners might do that. But how many? Enough to cost 700,000 jobs?

And let's not even get into the claim that "small" businesses are the primary engines of job growth in this country.

I did not know you could do this, but just tried it and it worked: if you enter "145 yen per liter in dollars per gallon" into Google, it will do both parts of the conversion for you.

Google is magic (though a different kind of magic than Romney's tax plan).

try Googling: [name of famous actor] Bacon number

@Lurker: The basis is arbitrary, but the SI forms a single, logical whole where the units relate to each other in a non-arbitrary way. This stands in stark contrast to the imperial system, where you have a terrible amount of ad hoc -units.

The flip side is that many of the ad hoc units in the American* standard system are that way because they relate directly to physical quantities we care about. That's especially true of units like atmospheres and BTU, and explains why there are a lot of ad hoc units hovering around the edges of pure SI measurements, like calories and torr. Even bar, which are easily defined in SI units, are most interesting because they're so conveniently close to an atmosphere.

*It's not the Imperial system! The Imperial and American systems are both derived from the earlier English standard, so they share a lot of units, but they aren't exactly the same. The most obvious difference is that an American gallon is 4 quarts while an Imperial gallon is 5, but there are some other ones lurking in there.

Fortunately, your metric/imperial fuel conversion errors were much less dangerous than those aboard the Gimli Glider.

In my experience unit conversions are one of the great killers of students in written exams. I also find that far too many students do not actually understand units and their relationships. At a time (while I did my PhD in chemistry) I was involved in preparing questions for written exams. I tried to insert some that totally relied on both, i.e. they were trivial in nature but required multiple unit conversions and in some cases deducting the relationship through the unit definition.

I think in most cases a rough conversion is sufficient (1 inch ~ 2.5 cm, 1 bar ~ 1 atm). When precision is needed it's calculator time anyway. The problem starts when units get confused or worse, the conversion is not accompanied by change of unit signs (or vice versa). I have often found mistakes like that (even in high value textbooks). I believe one probe to Mars got lost because sub-systems from different producers did not use the same unit system, one using the metric the other the imperial. And since machines only exchange numerical values it did not get noticed that the value for pounds is unequal to that of kilograms**.

As for gas prices, not that long ago it was the horror-beyond-horror proposal of the Green Party to deter people from car use by setting the price of gas at 5DM per litre. That would be 2.5€ today ignoring inflation. We are not far from that these days without any eco-nazi price fixing. Most Germans just shake their head when they hear the foam-at-the-mouth reactions of USians when their gas prices threaten to reach levels where people over here would be dancing in the streets*. Theactual gas bill in the US is of course not that different because US cars are much heavier, use less efficient engines and are used far more extensively even in similar circumstances. E.g. using a car where the typical European would walk or use public transport. Also Europeans tend to keep their shopping to portable amounts instead of buying bulk and thus needing 'light trucks' to get it home. For rural car use I would point at Scandinavia. I know from vacation in Norway that many homes are far from the next shop and shopping is a thing that will require hourlong drives (without traffic jams). Still gas is even more expensive there than in Germany but there are few violent revolts or campaign demagoguery about that.

*despite the fact that the 'freedom to drive' for Germans is what the 2nd amendment is for USians
**another notorious student problem. They take numerical values, do calculations and only add the unit signs when they have finished (or not even then). When the result is nonsense they either do not notice or do not realize that the error often crept in on the unit side.

I believe one probe to Mars got lost because sub-systems from different producers did not use the same unit system, one using the metric the other the imperial.

That would be the Mars Climate Observer.

And since machines only exchange numerical values it did not get noticed that the value for pounds is unequal to that of kilograms**.

I don't think that's quite right. Traditionally, we've made programming languages and tools that have really stupid type systems for dealing with physical quantities. But we can make better type systems in which the software verifies that no operation is ever performed on quantities of different units without conversion. For example, here's a really painful version.

In my experience though, Excel spreadsheets are even worse in this regard.

Just read Glenn Greenwald's reaction to Martha Raddatz's questions. I'd have been happy watching Biden dominate Ryan (or anyway, it sounds like that's what happened) but what Glenn calls the unexamined assumptions underlying Raddatz's questions would have been painful.

link

Of course she was way better than Lehrer (says the person who didn't watch either,but from all accounts an empty chair would have been better than Lehrer, though I suppose Clint Eastwood's little performance has cast a pall over any future role for empty chairs in our Presidential campaigns.)

And if you drive from Tokyo to Mt. Fuji you'll be paying 7000 yen for the privilege in road tolls. $87.50. So gas is a minor cost.

Frink Web-based Interface will do all kinds of unit conversions. Even implied multiple unit conversions.

Entering "1 gallon gasoline" and "pound TNT" will calculate the energy equivalent of one gallon of gasoline in pounds of TNT.

The Frink programming language has a huge library of units and unit conversions built into it.

Or....you could just think metric like everyone else in the world! Gallons are SO 1960s.

Yeah, but whose ever heard of a 38 liter hat?

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