Wikipedia:Reference desk/Archives/Science/2007 April 4

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[edit] April 4

[edit] Question about plant biology

I'm trying to determine the simple description for what loofahs are comprised of (protein, cellulose, ??). The loofah article took me to xylem, but that wasn't too informative either. Any help is appreciated. Anchoress 02:19, 4 April 2007 (UTC)

I don't know, but my guess would be it's cellulose, hemicellulose, and lignin. These three compounds seem to be the constituents of both wood (the leftovers of cell walls of secondary xylem) as well as plant cell walls in general. --Allen 02:38, 4 April 2007 (UTC)
There's probably a lot of fibre in loofahs, just by how the vegetable looks. --Bowlhover 04:38, 4 April 2007 (UTC)
Thanks Allen, hopefully someone will know the answer for sure. And thanks Bowlhover, but I'm hoping for something a bit more concrete. Anchoress 19:58, 4 April 2007 (UTC)

[edit] Cream Cheese

I'm not sure if this is the right ref desk, but... Ok, now this is a question that has been bothering me for a couple years now. I won't bore you with the long story, but suffice to say, my friends don't exactly trust my judgment. They think that cream cheese isn't a cheese. Besides the fact that the package SAYS it has cheese culture in it, they still don't think I'm right. I checked the cream cheese article, and though it is implied, it never actually says whether cream cheese is a cheese (or maybe it does and I just didn't look hard enough). I need a reliable source that CLEARLY states that cream cheese is a cheese. Thanks!! FruitMart07 02:36, 4 April 2007 (UTC)

The cream cheese article does more than imply that cream cheese is cheese, it says so right in the first sentence: "Cream cheese is a soft, mild-tasting, white cheese..." That said, I can't find a statement in the given reference that's quite so explicit. --Allen 02:45, 4 April 2007 (UTC)

They probably don't accept it as a cheese because it's spreadable at room temp, while most cheeses are solid at room temp. There are other soft, spreadable cheeses, like camembert, but they aren't common, at least in the US. The white color and mild taste are also atypical for cheeses in the US. StuRat 04:25, 4 April 2007 (UTC)

Cream cheese is called that because it's a mixture of cream and cheese. Personally I would call it a cheese just because it's made from milk but is much, much thicker than milk. It all depends on which definition of "cheese" and "liquid" you use. --Bowlhover 04:33, 4 April 2007 (UTC)
Cream cheese is a cheese made from cream (or nowadays, a mixture of milk and cream). It's not a mixture of cream and cheese.- Nunh-huh 04:38, 4 April 2007 (UTC)
I consider solidified milk as cheese. (That's how cheese is usually defined, isn't it?) --Bowlhover 05:12, 4 April 2007 (UTC)
Well, no. If you freeze milk, it's solid, but it isn't cheese. Cheese is a food made through the action of bacteria on curdled milk. But my point was that cream cheese is just cheese, it isn't cheese mixed with anything. If there's any mixing done (say milk & cream), it's done before the cheese is made. - Nunh-huh 23:59, 4 April 2007 (UTC)
  • Do your friends know how cheese is made? If they do, it's easy to prove cream cheese is a cheese, if not... you're in for the long haul. - Mgm|(talk) 08:10, 4 April 2007 (UTC)
And viola. The FDA officially classifies cream cheese as a cheese. Check it out here. I only hope your friends trust the US FDA's classification process. --Cody.Pope 08:24, 4 April 2007 (UTC)
My friends don't trust the FDA. "But the FDA classifies tomatoes as a vegetable!!" How dare they!?!? No, but seriously, I guess if they don't believe the FDA, who will they believe? I suppose I will have to accept the fact that I will never win. Oh well. FruitMart07 22:14, 5 April 2007 (UTC)

[edit] Making water flow visible

I have a set of water pumps that I can turn on and off, connected together with some clear flexible tubing, and I want to be able to see (very roughly qualitatively measure) how much water is flowing and through which pumps. To do this, I would like to add something to the circulating water (it just pumps water to and from the same tank) so I can see the flow. So something that...:

  • Neutrally buoyant in water
  • Doesn't damage the pump (about a 3/4" intake/outlet on the thing, so it's not puny)
  • Not extremely hazardous
  • Doesn't need to be replaced often (won't rot/decay)
  • Visible (obviously...haha)

I don't want a simple dye, because after running for a short time it will all be homogenized and pointless. I was thinking maybe glitter, but wasn't sure how close it would be to neutrally buoyant. Any ideas? -- atropos235 ✄ (blah blah, my past) 05:54, 4 April 2007 (UTC)

Plastic glitter, as seen in some novelty lamps?
Atlant 15:53, 4 April 2007 (UTC)
What kind of pumps are you using? Skittle 15:54, 4 April 2007 (UTC)

I'm assuming you won't be consuming this water. I suggest tiny Styrofoam balls, which are white and quite visible. You can break up some Styrofoam containers to get those little balls. StuRat 16:03, 4 April 2007 (UTC)

How about tying a few strands of tinsel in there? Varying lengths could give you an idea of the flow rate without adulterating the water itself like glitter would. --TotoBaggins 16:32, 4 April 2007 (UTC)

It all depends on what sort of pump you're using. Some pumps can handle debris in the water, while other types can't. --Carnildo 22:04, 4 April 2007 (UTC)

They're ballast pumps for a boat, so they should cope with small amounts of crap in the water. Tinsel may just get wound up in whatever mechanism it uses to pump, and styrofoam is extremely buoyant and would require a large amount of agitation to get them to mix. Glitter sounds best so far. -- atropos235 ✄ (blah blah, my past) 00:12, 5 April 2007 (UTC)
I would think in terms of a transparent cylindrical housing mounted in-line (but a little offset) in one of your pipes or hoses, in which something visibly spins. I've seen a glass-walled flow chamber in some fire sprinkler piping in a building I visit, although that one probably depends on there being air in that chamber or at least a few bubbles in the system. Or you could have a little brightly-colored plastic water wheel mounted in the chamber. You could probably make such a thing yourself, or I bet there are commercially-available ones.
In fact, a google search for "water flow indicator" turns up lots of possibilities. —Steve Summit (talk) 01:06, 5 April 2007 (UTC)


What if you mix oil in there? It will not homogenize, and you can even use food-coloring in the water to increase the visibility contrast. Nimur 20:50, 5 April 2007 (UTC)
Tiny bubbles of air from air forced through an underwater sponge stuffed on a pipe (blow through other end) should work nicely Polypipe Wrangler 09:26, 7 April 2007 (UTC)

[edit] White rice

Has white rice been processed to the point of have virtually no other components than starch or how much other stuff does white still contain after becoming white? (...and no this is not a metaphor for Black or Brown people who “turn” White and adopt White culture and ethnicity so don't even go there...) 71.100.6.150 10:16, 4 April 2007 (UTC)

White rice is still grown, as with all the rices. It is not made in a science laboratory. DDB 11:51, 4 April 2007 (UTC)

Yes, but the germ and the bran have been removed to 'turn' it from brown rice to white rice. Nutritionally, I've always heard that white rice is pretty empty, containing little fibre and few nutrients beside starch, these things having been in the germ and the bran. However, I would hope for a more definate answer from someone else. Also, you can buy white rice that has been treated or coated to add some vitamins back. Skittle 15:45, 4 April 2007 (UTC)
Okay, here are a couple of sites that claim to show nutritional info for white and brown rice. I can't speak for how reliable they are, but they suggest that white rice isn't as bad as I thought. The second site looks the best.[1] [2] Skittle 15:52, 4 April 2007 (UTC)

See here for a complete list of nutritional data for all types of rice: [3]. White rice is certainly less nutritious than brown rice, but is still low in fat, high in manganese, and provides energy over a long time period. Brown rice, of course, is all that and much more. One thing to watch out for is "browned rice", which is often fried white rice, not brown rice at all. StuRat 15:56, 4 April 2007 (UTC)

An advantage of white flour over brown is that it has a longer shelf life, due to the oily bran and germ being removed. The oils will go rancid after a while. The same probably applies to rice. --TotoBaggins 16:35, 4 April 2007 (UTC)

[edit] train with petrol

can the train run with petrol if yes why not

Trains can run with petrolium. They tend to use Diesel as (so I understand) the big engines aren't damaged by the stuff, as smaller engine cars are. DDB 11:46, 4 April 2007 (UTC)

I'm pretty sure DDB meant to link petrol (gasoline for Americans) as opposed to petroleum, which is crude oil). Trains do not use raw crude oil for fuel, but rather its refined products. Diesel fuel is generally less inflammable than petrol, which I would expect is a major concern given the quantities of fuel carried on trains. — Lomn 14:14, 4 April 2007 (UTC) Yep Oops DDB
Or, for those of us who speak American, Diesel fuel is less flammable than gasoline. --Carnildo 22:19, 4 April 2007 (UTC)
The Simpsons leads me to believe that Americans also use inflammable to mean 'extremely flammable'. 81.157.44.217 18:22, 5 April 2007 (UTC)

But, if you were asking if a train could be designed which would run on gasoline, then yes, that's quite possible, although not ideal. StuRat 15:49, 4 April 2007 (UTC)

Why stop there! Trains can be designed to run on whiskey too! 202.168.50.40 03:09, 5 April 2007 (UTC) You Mean Trains can run with us, too? DDB 08:59, 5 April 2007 (UTC)

Victorian trains sometimes ran on dead bodies, usually from egypt

Throw mummy in the boiler? Edison 15:14, 5 April 2007 (UTC)
If I bought a train over the Internet, only to find, upon delivery, that it ran on mummies, I would feel I had been e-gypped. StuRat 19:58, 5 April 2007 (UTC)
Diesel is a preferred fuel for trains than petrol/gasoline, because "Diesel engines tend to have their torque peak quite low in their speed range." This is ideal for a very massive vehicle like a truck/lorry or train. Nimur 20:55, 5 April 2007 (UTC)

[edit] Water Woes

HI. I can't seem to find out what the ideal minearal levels in water are. I have already found out what one can test water for (pH, calcium, lead, chlorine etc.), but it is useless sitting with the testers in hand but not knowing what they mean. If you could find a list with mineral levels, please? Thank you for your help!:-)

Ideal for what? Consumption? Generally I'd think that the less extra stuff is suspended in my water, the better. -- mattb @ 2007-04-04T13:22Z

It's complicated. Let's just take one example, iron. We need iron in our diet, so a bit in the water is good from that POV. Of course, you can also overdose on it, so you don't want too much in your water. Then there is the taste consideration. Water with a lot of iron in it tastes nasty. Then there is the aesthetics. Water with a high iron content looks "rusty" and leaves an orange stain on sinks and tubs. So, what is the ideal iron level ? It all depends. There are some minerals where the ideal level is probably zero, however, like sodium. Unfortunately, if you have a water softener you probably have quite a bit of sodium in the water. As little lead as possible is good, as is as little chlorine as possible (although if the chlorine is below a certain level, some other antibacterial agent is needed, or else you need to boil your water). I would expect a neutral pH (7.0) to be best. As much calcium as possible is probably good for you, but can also deposit in pipes over time and reduce water pressure. StuRat 15:39, 4 April 2007 (UTC)

Hmm. This [[4]] says you can have too much calcium. See also hypercalcemia (and look before you leap) :-)
That's true, but there generally has to be something wrong with a person to prevent them from eliminating excess calcium normally, such as kidney failure, for them to suffer the effects of hypercalcemia. StuRat 21:11, 4 April 2007 (UTC)

MikeT19278 23:11, 4 April 2007 (UTC)

[edit] identify this cabbage?

What kind of cabbage is this? http://bertilow.com/blogo/wp-content/uploads/2007/03/brasikofloroj2.png --Sonjaaa 11:17, 4 April 2007 (UTC)

I'm not a brassicologist, but it looks like Salad Savoy. --TotoBaggins 22:23, 4 April 2007 (UTC)

It looks like ornamental kale to me. MikeT19278 23:11, 4 April 2007 (UTC)

[edit] Slowing Earth's rotation

What would happen exactly if the earth rotation speed was reduced by 1 mph? Or even 100 mph?

Around its own axis? The day would become longer. This has, in fact, already happened, and continues to happen all the time. See tidal acceleration and day. Weregerbil 13:19, 4 April 2007 (UTC)

Well, I was talking about within a 24 hour period, the earth's rotation slowed by 100 mph. What exactly would happen?

The sun, if it were day, would move much slower across the sky, causing the sun-facing side of the planet to heat up and the other side to cool down. If the rotation speed decreased that much, ie: 100mph, there might be an ice-age on one side and desert conditions on the other. The days, weeks, months and years would become longer; seasons would change and probably a lot of species would die as a result. If it were only 1mph, people going about their normal lives would probably not notice. Think outside the box 13:47, 4 April 2007 (UTC)

Would gravity on Earth be affected - similar to the conditions in the movie It's All About Love?

The earth would still have the same mass, and as long as it was only the speed of the earth's rotation that changed, not its location, the gravity should be the same. Think outside the box 13:56, 4 April 2007 (UTC)
From an absolutely technical standpoint, there would be an effect due to the alteration of the moon's apparent orbit (that is, the moon will pass over a particular point slower or faster), so the period of the effects of the moon's gravity upon Earth will be changed. From a practical standpoint, tide charts will be off clock-wise. The average person is unlikely to notice anything amiss.
Also, note that "100 mph" is an impractical description of rotational speed -- what is that with respect to? A point on the equator moves around 1000 mph due to Earth's rotation, while a point near the pole moves around 1 mph from the same effect, yet both have the same length of day. Assuming you're meaning the equator example, though, night and day would be around 10% longer, and there would be around 10% fewer days per year. — Lomn 14:05, 4 April 2007 (UTC)
The lesser Centripetal Force needed to keep people going in a circle would affect the gravity felt by people on the equator, they would feel a stronger gravity, maybe something like 0.1m/s/s difference, if you like less of the force is making them go in a circle, so more total is felt as them being pulle ddown.. Not a whole lot. Capuchin 14:54, 4 April 2007 (UTC)
The difference would be a lot less than the difference between what you weigh when you stand at the equator (maximum centrifugal force) compared to when you stand close to one of the poles (zero centrifugal force). You certainly wouldn't notice any change. SteveBaker 15:36, 5 April 2007 (UTC)

If you're talking about the speed the Earth goes around the sun with (its orbital time, not its rotation time) the answer is that the earth would start to get a little warmer, because it would move to an orbit that is a little closer to the sun. The earth orbits the sun at 30 km a second, however, and a few mph isn't going to put much of a dent in it. WilyD 14:15, 4 April 2007 (UTC)

A million billion clocks would all be forever screwed up. Not unlike with the United States' Energy Policy Act of 2005.
Atlant 15:57, 4 April 2007 (UTC)
Well, maybe not 1,000,000 billion, but 300,000,000 million innocent people's internal clocks sure as heck are messed up. lol J.delanoy 01:23, 5 April 2007 (UTC)
EDIT. Well, since 300,000,000,000,000 people haven't existed since people first existed, I think I meant 300 million, not 300 million million. Oops.J.delanoy 01:25, 5 April 2007 (UTC)
Assuming we're talking about the rotational speed of the earth - measured at the equator - then a gradual slowing from around 1000mph to around 900mph would increase the length of the day by a couple of hours. This would likely do strange things to the weather and give people and animals permenant jet-lag - but the average amount of sunlight wouldn't change - so I don't imagine any drastic effects. Of course this assumes that the slowing down is very gradual. If it happened fairly quickly - the lateral forces on things like tall buildings and mountains and such might be utterly catastrophic! SteveBaker 15:36, 5 April 2007 (UTC)

[edit] Meteorology Software

What is the software that meteorologists use on TV for weather. I like the maps and radar. If you know, could you tell me where to get it and how much it is? Nick 15:37, 4 April 2007 (UTC)nicholassayshi

Can someone please answer this question. Nick 19:02, 4 April 2007 (UTC)nicholassayshi

You might try asking on one of the blogs here Weather Underground This is a weather site run but meteorologists, many of which have active blogs. —The preceding unsigned comment was added by Czmtzc (talk • contribs) 11:58, 5 April 2007 (UTC).
I used to know someone who wrote some of that software - but I've kinda lost touch with him. The software would essentially be useless to you without the radar systems that drive it. What you see on TV is just some presentation software that overlays the incoming raw weather radar data (which is not available to the general public) onto maps in various cute ways. At any rate, the software is only sold to a handful of TV stations - and since the cost of making it is high, and the number of copies they sell is low - we may deduce that it's going to cost many tens of thousands of dollars. Sorry - but I don't have exact figures. SteveBaker 15:29, 5 April 2007 (UTC)

[edit] buoyant force.

can the change in the temperature change the force of buoyancy that the liquid exhibits. please answer, i have wasted quite some time understanding this.

Consider where buoyancy comes from—a ship floats because the volume of water it displaces is equal in weight to the weight of the ship. Now, what happens to the weight of a given volume of water (its density) when you change the temperature? (Our article on Plimsoll lines may also give you a hint.) TenOfAllTrades(talk) 17:23, 4 April 2007 (UTC)

[edit] global warming and carbon dioxide level

I read a lot of papers about the relationship between carbon dioxide level and global warming. But i confuse if the carbon dioxide is mainly reason leading to global warming or just a temperature cycle? I also saw the film" An Inconvenient Truth". Responding to this film, many people felt scared, including me. However, many scientist are against Al Gore's opinion. So can you help us to figure out what the relationship between them?

That question belongs at the Reference Desk. Scottydude talk 16:50, 4 April 2007 (UTC)
  • The "scientists" who don't believe global warming is related to carbon dioxide and other greenhouse gases are "many", but they still represent a very insignificant part of the scientific community. This is hard to see because there are so many scientists, but it'd be easier to find a scientist named Steve who would explain that gloabal warming is the result of CO2 and other greenhouse gases than any scientist who'd say it's not true. The short answer is Global warming is the result of Carbon dioxide and other atmospheric pollutants increasing in the atmosphere due to human activity, and this fact enjoys widespread support in the scientific community. Alternative theories exist, but have no significant support. WilyD 17:45, 4 April 2007 (UTC)

Global warming has aspects that are from carbon dioxide, cf Venus. However, global warming is almost entirely Solar in nature. As it becomes apparent the solar system was heating up until '98 then the carbon dioxide link becomes rhetoric. Mars heats up. DDB 21:01, 4 April 2007 (UTC)

If you'd like some actual numbers of the scientists for/against the issue, here is an essay from the journal Science, on a paper examining the subject. 928 refereed papers were reviewed, published between 1993-2003 inclusive, and compared against the consensus position (defined by the IPCC as "Human activities...are modifying the concentration of atmospheric constituents...that absorb or scatter radiant energy... [M]ost of the observed warming over the last 50 years is likely to have been due to the increase in greenhouse gas concentrations"). The only condition for their inclusion was they were database listed with the keywords "climate change" .
The paper found that "75%...either explicitly or implicitly accept[ed] the consensus view" and "25% [took] no position on current anthropogenic climate change". "Remarkably, none of the papers disagreed with the consensus position." So there you go: 75% agreed, 25% did not express an opinion, nobody disagreed. Obviously they didn't include every paper ever, but it's a decent sample. Many scientists express opinions of things, but until/unless that opinion has been peer-reviewed it's not generally considered as being worth much. Spiral Wave 00:43, 5 April 2007 (UTC)
I talked about Oreskes's essay back in September. It seems the quote is fully relevant here as well. "Oreskes's activity had a few faults. I do not believe he explained the statistical methods in which he selected the abstracts. The rest are explained in the following links, and thus, I conclude his activity does not stand up to scientific scrutiny.[5][6][7] I don't see why a flawed argument toward argumentum ad populum is doing here either." Also, I suggest [8] about the greenhouse effect, carbon dioxide, and more. Also, for some other numbers, you'll see that the skeptics won. [Mαc Δαvιs] (How's my driving?) ❖ 01:53, 5 April 2007 (UTC)
Ah, thank you. I don't suppose you remember the date/subheading? You're as like to remember as anyone. Spiral Wave 08:16, 5 April 2007 (UTC)
[9] [Mαc Δαvιs] (How's my driving?) ❖ 16:14, 5 April 2007 (UTC)
However, many scientist are against Al Gore's opinion. - I suggest you dig out the DVD and watch it again. Al Gore addresses this precise point in his exposition. The word many here is misleading. Many meaning more than 10 people? Yes, more than 10 reputable scientists do not agree with global warming. Many meaning more than 1% of all scientists? Hell no! Several studies of peer reviewed scientific papers have shown that much less than 1% of scientists disbelieve in global warming...a negligable fraction of them do in fact. An Inconvenient Truth has a precise reference to two studies that were done to answer the question "Do many scientists discount global warming?" - neither of them found any significan number of dissenting scientists. Yes, global warming is scarey - but that doesn't make it untrue. SteveBaker 15:24, 5 April 2007 (UTC)
Why don't we read Richard Lindzen's article in the Wall Street Journal? James Hansen also wrote one for NASA a bit ago that poses the opposite opinion[10]. [Mαc Δαvιs] (How's my driving?) ❖ 16:14, 5 April 2007 (UTC)
Since the original question was about CO2 connection to temperature, some say it is tightly, some say it is hardly. Sample:[11][12] [Mαc Δαvιs] (How's my driving?) ❖ 17:48, 5 April 2007 (UTC)

[edit] energy saving conundrum

as energy efficient lights require a surge of power to start up and then have a lower rate of power usage as they operate, is it more energy efficient to turn them off and on as you leave and enter rooms, or to leave them on while you are pottering around the house? Calorine 19:07, 4 April 2007 (UTC) caroline

Do you mean CFLs? That article is tagged as needing some work regarding neutrality, but I see no indication that there is any kind of surge required at startup. There are several other pros and cons listed in the article and on its talk page. --LarryMac 19:16, 4 April 2007 (UTC)
The Mythbusters did this one. The answer is, unless you only plan to leave the room for about 200 ms, it's more energy efficient to turn the lights off when you leave. Common sense triumphs! -- mattb @ 2007-04-04T19:25Z
From what I've heard about energy saving lights it is better to leave them on, especially if you will be needing them again very soon. Every time you turn one on it does requires that initial surge of power to heat and light up the filament. But also, in the nature of being energy efficient, don't have them on during the daytime if you can help it. Try to use the natural light! :) Think outside the box 19:28, 4 April 2007 (UTC)
What kind of energy saving lights are you speaking of? CFL's don't have a filament. --LarryMac 19:35, 4 April 2007 (UTC)
Compact fluorescent lights have a very long lifetime, but only if they are not turned on an off a lot. Incandescent bulbs have about 1/10 the lifetime of a fluorescent, and use three or four times the power to produce the same brightness, but might actually last longer if turned on and off frequently. Edison 19:52, 4 April 2007 (UTC)
  • One question is what are you planning to consider in the total energy costs. Are you going to consider only the electricity used or other energy costs as well? For instance IF switching the light on and off leads to a shorter life time, then you may wish to include the energy costs of manufacturing a new light bulb, shipping it to the retail store, you going to pick it up, etc. See cost accounting and Total cost of ownership. There are also opportunity costs to consider in terms of what you could be doing instead of flipping on and off the light switch.  :-) Johntex\talk 20:02, 4 April 2007 (UTC)

oh no, this is precisely the arguement my boyfriend and i are having! yes the total cost is relevant, we both have difficulty sitting still and what with toilet breaks, going to get drinks etc it often seems we follow each other round turning lights on and off. i am firmly in the camp of leaving necessary lights (the stairs) on, believing turning on and off reduces life span, thanks Calorine 20:25, 4 April 2007 (UTC)

If you do some research and find some indications on how severely switching CFLs on/off affects their lifetime, modeling the total cost of leaving them on vs off wouldn't be a difficult endeavor. Anyway, this is part of the reason some folks are working hard to get LED lighting up-front cost-competitive with CFLs (it's almost there). Aside from the fact that they consume far less energy for comparable optical output, there is no significant damage incurred to an LED by switching it on/off! (yeah yeah, nasty semiconductor fabs... mercury ain't so friendly either) -- mattb @ 2007-04-04T21:14Z

[edit] Steel made from rocks?

I work in a school and during the rocks and mineral unit a student mentioned that steel comes from rocks, and another teacher confirmed this. I was a little apprehensive to believe this. My logic was (in simpleton terms) that steel comes from oxidized iron, which is an element. Furthermore, rocks are made of minerals. Now is an element a mineral? I dont really know. But does steel come from rocks? Is that technically true? Dont let me be wrong in front of these kids!

Thanks 65.200.190.242 19:27, 4 April 2007 (UTC)moe.ron

Steel comes from an ore called hematite which is in some rocks. See Basic oxygen steelmaking for how its converted, and have a look a this image of iron ore, the base component of steel. Think outside the box 19:37, 4 April 2007 (UTC)
iron is an element, it is smelted from the ore haematite a rust colured rock. combined elements make up minerals which make up rocks
All minerals are made up of elements. In fact, all matter is made up of elements, so all rocks are too. Johntex\talk 20:03, 4 April 2007 (UTC)
All matter is not made up of elements, elements and matter are both made of atoms. Think outside the box 20:11, 4 April 2007 (UTC)
Yes, all matter is made up of atoms, but you are drawing the wrong conclusion.
Any given atom is of one of the elements. An atom is just an instance of an element. An oxygen atom is an instance of the element Oxygen and so on. You can't find any atom that is not an element. Therefore, anything that is made up of atoms is also made up of elements. Now, elements are combined into molecules so not all elements are existing in their elemental state.
For instance, water is a molecule made up of oxygen and hydrogen. It is correct to say that water is made up of those two elements. Everything you see as you look around you is made up of the various elements in various combination. Johntex\talk 20:22, 4 April 2007 (UTC)
(Note, when I say all "matter" is made up of atoms, I am speaking of what humans generally hold to be matter - I am ignoring the fact that energy can be converted into matter, etc. Those types of distinctions are not relevant to the question about steel).
How about electrons? Not atoms, but mass.

Johntex\talk 20:25, 4 April 2007 (UTC) steel is iron with a small amount of carbon added to improve tensile strength Calorine 20:27, 4 April 2007 (UTC)

Yes, that is right. Steel is iron mixed with carbon, typically. Both iron and carbon are elements. Johntex\talk 20:54, 4 April 2007 (UTC)

Thanks to everyone for their responses. But I guess I may have mis-communicated my question. I guess Im just wondering does, technically speaking, steel come from rocks? I, disagreeing with the class, feel that it does not because steel comes from iron which is an element where as rocks are made up of minerals.

The really, really short answer is "Yes, Steel comes from Rocks". SteveBaker 22:31, 4 April 2007 (UTC)
An inbetweenedly longer answer is that steel comes from iron which comes from iron ore which is a mineral and a rock. —Steve Summit (talk) 23:42, 4 April 2007 (UTC)
The slightly longer explanation is that a "Mineral" is just a fancy name for a collection of different chemical compounds in a rock. Iron is an element that is found in some rocks - typically bound up in a chemical compound with other elements. Steel is mostly iron. So - you take your rocks (that are made from minerals that contain compounds that contain iron)...you smash them up into tiny bits - you heat it and add various chemicals - and you get out iron. You add more stuff to the iron to make steel. Yep - steel comes from rocks. SteveBaker 22:31, 4 April 2007 (UTC)
A bigger-picture answer is that worrying about what something "is" -- where your definition of "is" is just "what is its name?" or "what category does it belong to?" -- can be a meager, unsatisfying, and ultimately unimportant kind of knowledge.
For example, people often talk about "Rocks and Minerals". Now, is granite a rock or a mineral? Is iron ore a rock or a mineral? Is a diamond a rock or a mineral? It is or it isn't, depending on what your definitions of "rock" and "mineral" are.
Don't get me wrong, nomenclature and taxonomy are both important. Having a name for something can be much better than not knowing anything about it at all. But as Richard Feynman was fond pf pointing out, if all you know about (say) energy is that its name is "energy", that doesn't tell you anything -- it might as well be "wakalixes".
What's most important is not having a single, unambiguous definition of what a "rock" is, or a single, unambiguous definition of what a "mineral" is, or a single, unambiguous, yes-or-no answer as to whether a chunk of granite, a chunk of iron ore, and a diamond are one or the other. What's most important (if you're really interested in chemistry and/or mineralogy) is to understand the chemistry of these materials, and to explore the way they're similar to and different from each other, and from other rocky and/or mineraly substances. Then, as an afterthought, you can understand whether iron ore is or isn't a rock under some one person's particular definition of "rock", bearing in mind that there's probably more than one definition of "rock", meaning that the real answer might be "yes or no, depending on whose definition of 'rock' you're using". (And this is why I'm claiming that merely knowing one answer to the question "is iron ore a rock?" is at best a meager kind of knowledge.) —Steve Summit (talk) 00:05, 5 April 2007 (UTC)
Whilst that's all true (and I'm a big fan of Feynmann's view on names-of-things-not-telling-you-anything-about-the-thing - which he actually got from his father incidentally) - we catagorically cannot allow this loophole to let our questioner off the hook. If it looks like a duck and quacks like a duck we may assign the term "duck" to it even though that is a vague and unscientific appellation that in itself carries less meaning than the sound and appearance of what we may tentatively label as a highly evolved dinosaur. If your class says "Steel comes from rocks" - you cannot, must not, tell the kids that they are wrong - they are absolutely 100% right: Steel is made from iron and iron comes from iron ore which is indeed a rock. If you tripped over a large lump of iron ore - you'd say "Damn! I hit my toe on a rock." - which is good enough for me (and for Feynmann!). You have to eat a large slice of humble pie snd confess to the kids that they know more on this subject than you do! Sorry! SteveBaker 15:15, 5 April 2007 (UTC)
Ah. I missed that the original questioner was not a student. Most of the people I come across who are seemingly too focused on arbitrary definitions (and it's a lot of them, which is why it's sort of a hot button with me) are uncreative students who are desperately trying to answer overly definition-based questions posed by equally uncreative teachers. So, no, the original questioner doesn't get off the hook so easily, and not only should he not teach his students that iron ore isn't a rock, he shouldn't merely teach them that iron ore is a rock, either. Better to teach them what it means to be a rock, so that they can understand not only that iron ore is a rock and why, but also figure out next week that pegmatite (which neither he nor they had heard of, and which wasn't on the initial lesson's list of these-are-rocks) is a rock, too. —Steve Summit (talk) 03:03, 6 April 2007 (UTC)
  • And sometimes, the rocks are made of steel;
    Meteorite
    Meteorite
    --BenBurch 23:59, 4 April 2007 (UTC)
    NO! Not steel! Meteors are often made of iron - but steel is iron with a fairly precise amount of carbon added to it (0.02 % and 1.7 % by weight). You could make steel from an iron meteor though. (A pure steel meteor would be an amazing thing!) SteveBaker 15:04, 5 April 2007 (UTC)

If you drag a magnet around in different soils you can collect minerals containing iron. Polypipe Wrangler 09:47, 7 April 2007 (UTC)




[edit] Time

hi, Now that those pesky babylonians are long gone, i was wonderdering if there ever has been (or is) a movement to "metricise" time? Also, if one country decided to use this system and others didnt, when was the last time that the world hasnt used the same time system? (obviously there are several different calendars, but i'm talking about on a minutes and hours level). thanks 87.194.21.177 19:54, 4 April 2007 (UTC)

On a side note - what happens when the day is no longer the same as here on Earth (I.e. approximately 24 hours long)? Would decimal time become commn if we send humans out into space for long time periods? Timekeeping on Mars is an interesting read. Johntex\talk 20:07, 4 April 2007 (UTC)

There are problems/issues with Decimal numbering. Because 10 is not prime, it's decimals are not unique fractions, hence 0.2 is 1/5th, equivalent to 2/10ths. In a number system based on 11 or 7, this is not an issue. A binary number system doesn't have that issue, but it attracts too many digits for small numbers. DDB 20:53, 4 April 2007 (UTC)

Are you saying that has a particular imact on time keeping, or are you making a more general mathmatical observation? Johntex\talk 20:57, 4 April 2007 (UTC)

Johntex, I'm saying that if we rationalise our time system, then we should probably not go to decimal. I think a migration to base 7 or base 11 would have advantages, although, admittedly, unlikely in the forseeable future. DDB 08:52, 5 April 2007 (UTC)

That's the same as saying the current system won't work, because you could watch a half-hour TV show, or a two-quarter-hour TV show and have it mean the same thing. It's still the same unit of time. Be more specific about why a decimal system wouldn't work for time. Also, binary would have that issue, where it would have to go into repeating binary 'decimals' (negative powers of two) for certain numbers. --138.29.51.251 10:36, 5 April 2007 (UTC)

there was also roman time which had 12 hours in a day and 9 in a night, making 21 overall

Decimalising time has (in some senses) already happened. In SI units, time is measured in seconds, kiloseconds, megaseconds, milliseconds, microseconds and so on. Durations shorter than a second are pretty much always in SI seconds - although the jiffy has been somewhat popular in some computer systems. Units like weeks, days, hours, minutes and so forth are not really approved of for scientific use (although you see them all the time in imprecise timings). SteveBaker 14:58, 5 April 2007 (UTC)
Note that while metric base-10 systems are useful in some ways, the number 10 is not the best choice if you are interested in subdividing easily into whole numbers. The number 12 turns out to be the smallest number with 6 divisors -- perhaps part of why it is so common (musical notes, hours, eggs, months, inches, etc). The number 60 is also a great choice for subdividing. It is the smallest number with 12 divisors, including all the whole numbers from 1-6. There are pros and cons to using these numbers, as with metric base-10. Quick and easy subdivision calculations are also part of why units like the acre are still common and useful. Pfly 19:44, 5 April 2007 (UTC)
Yep - I agree 100%. Decimalisation has always been a retrograde step compared to the older base-12 and base 60 systems. 10 is divisible by 2 and 5 only. 12 is divisible by 2, 3, 4, 5 and 6. Much more convenient. However, we'd need to change our arithmetic over to base 12 and that's just not going to happen. Alternatively, if we believe that computers are here to stay then we might consider base 16 (hexadecimal). Darn these 10 fingers! But given that we use base 10 numbers - we're stuck with decimalised units whether we like it or not. SteveBaker 04:29, 6 April 2007 (UTC)
So... in which number system is 12 divisible by 5? :D Shinhan 18:57, 6 April 2007 (UTC)
Ooops! Brain slip. Sorry! SteveBaker 16:51, 7 April 2007 (UTC)

[edit] oxygen

I am wondering if oxygen is used to get rid of carbon dioxide.70.241.240.30 20:52, 4 April 2007 (UTC)

Can you be mores specific, please? What type of situaiton are you referring to? Johntex\talk 20:55, 4 April 2007 (UTC)
(edit conflict) In general, no: oxygen and carbon dioxide do not react with each other under normal conditions. However, the question is a bit ambiguous...what do you mean by "get rid of" (permanently remove from the environment to solve a greenhouse-gas problem, remove from exhaled breath, remove from a reaction vessel, etc.). DMacks 20:56, 4 April 2007 (UTC)
Well, plants can absorb carbon dioxide and release pure oxygen, so you could say plants 'get rid' of carbon dioxide by using the carbon to build their wood/stems etc.
Carbon dioxide poisoning is treated with oxygen, too. Aaadddaaammm 23:55, 4 April 2007 (UTC)
The only reason oxygen is used to treat corbon dioxide poisoning is because people nee to breathe oxygen. J.delanoy 01:28, 5 April 2007 (UTC)
  • Also, in carbonated drinks pumping in enough oxygen means the carbon dioxide gets expelled, but that's more pressure and basic physics than anything else. - Mgm|(talk) 12:43, 5 April 2007 (UTC)

[edit] Question about glasses and ear defenders

My dad works as a gardener outdoors but, due to the sunlight, which is damaging his retina, he has to wear glasses which dim the sunlight. However, he also works in a particularly noisy environment involving machinery. As such, he has to wear ear defenders/protecters. However, these ear defenders press heavily on the bones next to his ear. Does anybody know of any types if ear defenders/protectors which would work well with spectacles. If nobody can suggest anything, suggestions would be appreciated. Thank you, in advance, HadzTalk 22:14, 4 April 2007 (UTC)

You might want to consider different sunglasses, instead. I believe there is a model which has an elastic band (which goes around the back of the head) in place of the usual ear pieces. StuRat 23:03, 4 April 2007 (UTC)
Many workers in very noisy environments wear Earplugs. In the U.S. these are subject to approval by OSHA and can reduce noise levels about as much as the over the ear protectors. See [13]. An example (only one of many companies) is [14] which reduces noise 33 dB. They should not interfere with eyeglasses in any way. Edison 23:31, 4 April 2007 (UTC)
Dad says he has psoriasis which affects his ability to place things in his ears, apparently it aggravates his condition. --82.36.182.217 00:12, 5 April 2007 (UTC)
Any otologist goes by the humorous mantra "never stick anything smaller than your fist in your ear canal." They recommend silicone earplugs. [Mαc Δαvιs] (How's my driving?) ❖ 03:15, 5 April 2007 (UTC)
Check out what foundry workers wear - combined ear defenders and glasses. failing that, the foam ear inserts that are commonly used int he food procesing industries are pretty effective. Failing that, see a specialist.Greglocock 08:55, 5 April 2007 (UTC)
I have seen special eyeglasses without earpieces which attach inside the faceplate of a gas mask or respirator, so I suppose it is possible they also make eyeglasses with shortened earpieces which attach to the headpiece of the earmuff-style hearing protectors. It should not even be all that complicated. An optometrist might be able to check for the availability of same. If not, then invent it and make a fortune, since theere is a clear need of not having the earpiece under the rubber cup of the hearing protector, which would probably interfere with the effectiveness of the hearing protection. Edison 15:12, 5 April 2007 (UTC)

He has my sympathy, I have a hearing protector with two wires that go over the head (not a piece of plastic) . It can be bent and stretched until it is comfortable.Polypipe Wrangler 09:54, 7 April 2007 (UTC)