atomic_fungus (atomic_fungus) wrote,
atomic_fungus
atomic_fungus

#5027: The new year's resolution

My new year's resolution is to do something about the damned basement.

It's going to require some heavy lifting, of course, because it's a friggin' mess down there, but having successfully cleared 80% of the garage of stuff I don't use (and won't) and which no one wants, I'm setting my sights on doing the same for the basement.

That one shouldn't take as long. The scale is smaller, and none of it is stuff I have to worry about other people wanting. I just need to do it.

* * *

Yesterday I saw a tank truck of liquid hydrogen cruising down the road, and I wondered how much it weighed.

Oxygen is 89% of the weight of water. A water molecule is two hydrogen atoms and one oxygen atom; the hydrogen atoms have a total weight of about 2 AMU but the oxygen atom is 16. When you have a mole of water (18 grams), 2 grams of it is hydrogen; the rest is oxygen.

So, assume a 9,000 gallon capacity. 9,000 gallons of water weigh 72,000 pounds, or 36 tons. 9,000 gallons of liquid hydrogen, however, weigh 2,400 pounds--barely 1.25 tons.

All else being equal, of course, the truck can't actually carry 9,000 gallons of liquid hydrogen because the tank has to be super-insulated and-and-and. Even if we assume that the trailer is heavier than a typical tank trailer it's still not going to be as heavy as a truck full of water would be.

This is the problem with liquid hydrogen as rocket fuel: it's energetic, all right, but it's not dense, and it takes a lot of it to do anything useful. That's why the space shuttle had that huge external tank; most of that tank was for liquid hydrogen. When you look at the cutaway view of a space shuttle tank it seems strange that the hydrogen tank is so much larger than the oxygen tank--it doesn't look like there's nearly enough oxygen to burn all that hydrogen--but it's not when you understand the relative densities involved.

That's also why the Saturn V first stage burned kerosene with liquid oxygen: kerosene is an excellent fuel for low-altitude operations; it's dense and fairly energy-dense, especially when burned with pure oxygen. Furthermore it doesn't require any special handling since it's liquid at room temperature, and it's a hell of a lot cheaper than liquid hydrogen. (The kerosene used for rocket fuel, RP-1, is highly refined, but it's still the same stuff that people used to light their homes with.)

Science!

* * *

Last night I got out of work about forty minutes late thanks to a guy who called about ten minutes before my quitting time. It wasn't that he was a bad guy; he just found it necessary to tell me his life story every thirty seconds. A call which could have taken perhaps fifteen, twenty minutes instead took three times that long.

Me: Well, yes, if we make that change to your plan it would lower your bill by about $120, sure.

Him: blah blah blah blah blah blah blah blah AT&T bought DirecTV blah blah blah I pay my bill in cash blah blah blah blah blah BLAH BLAH BLAH BLAH BLAH BLAH BLAH BLAH BLAH BLAH BLAH BLAH BLAH BLAH BLAH BLAH BLAH BLAH BLAH BLAH BLAH BLAH BLAH BLAH

Me: (thinking) HOLY SHIT WILL YOU JUST SHUT UP ALREADY

Him: blah blah blah blah blah blah blah blah AT&T bought DirecTV blah blah blah I pay my bill in cash blah blah blah blah blah BLAH BLAH BLAH BLAH BLAH BLAH BLAH BLAH BLAH BLAH BLAH BLAH BLAH BLAH BLAH BLAH BLAH BLAH BLAH BLAH BLAH BLAH BLAH BLAH

Me: Yes, of course. So--

Him: blah blah blah blah blah blah blah blah AT&T bought DirecTV blah blah blah I pay my bill in cash blah blah blah blah blah BLAH BLAH BLAH BLAH BLAH BLAH BLAH BLAH BLAH BLAH BLAH BLAH BLAH BLAH BLAH BLAH BLAH BLAH BLAH BLAH BLAH BLAH BLAH BLAH

Me: *sigh*

...and yes the guy repeated himself, excessively. I didn't count but he must have explained the circumstances of his account some dozen-odd times, how it used to be in one person's name because he doesn't like credit cards and is personally opposed to plastic cash, but he had to move it to this other person's name, who is graciously letting him use his credit card.

Here's my thing: if you pay your account in cash, why do you need someone else's name on it?

Ultimately, I don't really care, though. Sure, it was frustrating to be held at work by someone when it was my Friday night and I just wanted to go home, but I made a little extra money and--as I said--he wasn't a bad guy. He wasn't upset or angry about the size of his bill; he just wanted it explained.

When I could get a word in edgewise.
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