Clean Water for Haiti

A couple from our church are going to Haiti in January to work with Clean Water for Haiti. Their primary goal is the distribution of biosand filters. The picture is a cutaway version on display in the lobby. It seems like a reasonable thing to do. We had a sand filter on our pool in Phoenix. Of course we also used chlorine, so it's not exactly the same.

A quick Google turned up a couple other outfits working on the same problem, some have bigger goals, like city water supplies, some are more specialized, like water for a hospital. It's funny much of the world is having trouble getting clean water. With Haiti I can kind of understand it, the place has been a rathole forever. Why is that? What is it with these third world countries that they cannot take care of themselves?

Update March 2016 replaced missing picture.

Blastolene Rides Again

Streetfire's latest newsletter had a video tour of the SEMA (Specialty Equipment Manufacturers Association) show. For the Best of Show they picked the latest creation from Blastolene, creators of the infamous Blastolene Special.

Piss'd Off Pete

Now there's a hot rod!

Update January 2017 replaced missing picture, removed dead links.

Quote of the Day

"Every intelligent family has one member who is crazy."

I didn't think much about it when I first read it, but it has stuck with me for two or three days now, so I thought, maybe I should post this. It certainly seems to be true. Of course, there are varying degrees to crazy, and one person's crazy can seem perfectly rational to another.

It's not a quote, exactly. That's just the way I remember it. I went looking for the source, but I couldn't find it. Anywhere. I've been working on The Club Dumas and that's where I thought I saw it, but it didn't pop up when I skimmed through it, and Google Book Search couldn't find it, so I don't know where it came from. Maybe I dreamed it. I had a pretty vivid dream last night, but I can't remember it. Who knows?

Velocity, Part 2

I've been trying to understand why Alpha particles (from Americium 241 which is used in smoke detectors) is so harmless and Neutron radiation is so dangerous. Especially since Alpha particles weigh four times as much as neutrons and their initial velocity is higher. Fast Neutrons travel around 15km/s (kilometers per second) and Alpha particles travel around 20 km/s.

The essential difference seems to be that Alpha particles carry an electrical charge, and Neutrons, being neutral, do not. Still, I wonder. Neutrons can travel miles in air before they hit anything. Alpha particles only manage to get a couple of inches. It must be electrons, which are the only particles that carry a negative charge. But under normal circumstances, all the electrons are busy, so just how does this work? It's just weird.

Atoms have a tiny nucleus that is surrounded by a cloud of electrons, much like you could have a cloud of fruit flies around an orange, except the orange is the size of a mustard seed, and the cloud is as big as your house.

When an Alpha particle is kicked out of a heavier atom due to radioactive decay, it travels through the cloud surrounding this original atom and it doesn't pick up any electrons there. It just zooms right through the cloud, otherwise we wouldn't be having this discussion. This leaves the atom with a couple of extra electrons, and who knows what happens to them. I imagine they will probably wander off with some positively charged swain eventually.

But now our positively charge Alpha particle is on it's way at measurable fraction of the speed of light, about 5% actually. Light travels at about one foot per nanosecond. (Number of feet per mile (5280) times the speed of light in miles per second (186,000) is roughly equal to one billion feet per second, and there are a billion nanoseconds in one second. So one foot per nanosecond, more or less.) So our Alpha particle travels about 5/8 of an inch in one nanosecond. (Another way to think of a nanosecond is to look at your computer. A computer that operates at one gigahertz (GHz) does one operation per nanosecond. A computer that runs at 3 GHz will do three operations in one nanosecond.)

Atoms in air are widely separated, so an Alpha particle is liable to go some distance before it actually hits one. When it does impact one it will most likely just go through the cloud of electrons (big as a house). It is unlikely to hit the nucleus (small as a mustard seed). Now it is unlikely to pick up an electron from this, after all, when it was kicked out of it's parent atom it didn't manage to pick up any electrons. And even if it did pick up one, it's not going to slow it down. Compared to an Alpha particle an electron weighs next to nothing. It's like comparing a life preserver to the Titanic.

So I think what we've got going on here is electron drag. Atoms taken as a whole are neutral, they have the same number of positively charged protons as they do negatively charged electrons. At some distance from the atom, these charges cancel each other out and no charge is apparent. But the protons are all in the nucleus, and the electrons are all in the cloud, so when you get right up close to an atom, closer than the electron is to the nucleus, you are going to feel some of the negative charge from the electrons. This is what is dragging on the Alpha particle and slowing it down. It's not much force, but atoms are tiny, and even a small amount of air contains zillions of them. So as the Alpha particle travels through air, every few nanometers it comes close enough to an air molecule that it feels the attraction from the electrons, and this slows it down just a hair. You do that a few zillion times and pretty soon your charged alpha particle is at rest. It may even have captured a couple of electrons, making it neutral, but leaving a couple of air molecules ionized.

I would check my numbers, but I am pretty much worn out from trying to sort all this out. I spent several hours yesterday trying to find the information I wanted and then I finally found this statement (on this page):

Oxygen molecule flies into nitrogen gas

"How far can we expect the O₂ to get before it hits an N₂? The average distance before a collision is the mean free path. Let’s try to picture how much room there is to fly between these fixed N₂ spheres. (Bear in mind that the picture above should be three-dimensional!) We do know that if it were liquid nitrogen, there would be very little room: liquids are just about incompressible, so the molecules must be touching. Roughly speaking, a molecule of diameter d will occupy a cubical volume of about d³ (there has to be some space left over—we can pack cubes to fill space, but not spheres.)

"We also know that liquid nitrogen weighs about 800 kg per cubic meter, whereas N₂ gas at room temperature (and pressure) weighs about 1.2 kg per cubic meter, a ratio of 670. This means that on average each molecule in the gas has 670 times more room—that is, it has a space 670 times the volume d³ we gave it in the liquid. So in the gas, the average center-to-center separation of the molecules will be the cube root of 670, which is about 8.75d. So the picture is a gas of spheres of diameter d, placed at random, but separated on average by distances of order 10d. It’s clear that shooting an oxygen molecule into this it will get quite a way. Let us emphasize again that this picture is independent of the actual size of d: we’re only considering the ratio of mean free path to molecular diameter."

So I stand by my supersonic-aircraft-hooking-a-zillion-mailbags-and-the-straps-break analogy.

Update January 2017 replaced missing image.

States Rights

People are just plain disagreeable. Well, gee, thanks, Mr. Obvious.

There has always been some talk about States Rights, about how the States should have more power and the Federal Government should have less. That always seemed like a good idea to me, and I wondered why it wasn't that way. Eventually I figured it out. Working in government, trying to get decisions made, bills passed, laws enacted, is a tedious, unpleasant business. Most people won't bother unless the stakes are high enough, and the stakes are much higher in the Federal Government than in the State Governments. Our State Government (Oregon) is a prime example. We have more obstructions mired in the 19th century than we have people who are willing to step up and take care of business. So they spend years quibbling while the whole state is crumbling around our ears, and people quit paying attention to them and start looking to the Federal Government to get things done. Gripe about the Feds all you want, they do manage to get things done. They might not be the things you want done, but by God, things are gonna happen.

P.S. Spell checker complained about the th in 19th, but it let gonna go. Huh.

Spider for the Day

I found this one in the basement. He's pretty good size, about two inches tip to tip. He looks a lot like another one I snapped a couple of weeks ago. Could it be the same one? Or is there an army of spiders out there, just waiting for their chance at a warm spot?

This picture is not as clear, but I like what Picasa's color correction did to the abdomen: gave it that nasty blue color. I am pretty sure the white dots are reflections of the flash.

Update March 2016 replaced missing picture.

Velocity, Detour, Part 2

Grumman EA-6B Prowler

Rocky Humbert found a story by the New York Times that contains a brief description of the damage that the Prowler aircraft suffered when it cut the gondola cable in Italy 11 years ago. Thanks, Rocky! The story also contains a place for a picture, but there is no picture, only a description of what the picture shows, and the aircraft is not in it. I imagine the military has a bunch of photos, but no telling where they are. (This picture is of a similar aircraft, not the one involved in this incident).

So we have a report that there was damage to the aircraft, so maybe it did happen as they say and it wasn't the North Koreans or the Mafia. That airplane wing must be made out of some pretty tough stuff. Well, it is a military aircraft, they do have have hardpoints on the wings to carry things like bombs and stuff, and it has folding wings so, okay, the wing was tough enough to hang on until the cable broke. Still, I wonder about just how the cable broke. It's going to be under considerable tension. I imagine the cable itself weighs a few tons, and then we have the gondola hanging from it, which adds more tension. Now we strike the cable with an aircraft wing traveling 500 MPH, which is like 750 FPS (feet per second). The cable must have parted almost instantaneously. If it had held on for more than a couple of milliseconds, the airplane would have slewed around and probably crashed. I don't think the cable was cut so much as it just snapped. Hitting the cable must have increased the tension on the cable to the point that it failed.

Of course, I could be all wet. There may be an internal structure in the wing that acted like an ax blade and severed the cable.

Update January 2017 replaced missing picture.