CaptainPanic

http://nl.wikipedia.org/wiki/Global_positioning_system

I agree with Klaynos. But to show the extreme case, you can fly a paper airplane over a subwoofer

The author might write "brief and precise" though, which is merely 2 extra words. While reading 2 extra words might take me an approximate 1 additional second, looking up a word takes me perhaps up to a minute. I totally agree that in some cases where clarity suffers from the use of simpler words, it should be avoided. But in many cases it's a matter of sounding more posh, expensive or even just a matter of a professor who cannot pass on a draft paper as a final version without changing a few words. I fear we're not on the same topic here. I don't mean that articles should be filled up with irrelevant blabla. I mean that it generally takes less words to combine several sentences into one huge one. To cut these sentences up again into shorter sentences means you need a few extra words. It makes it easier to read (in a way children's books are easier) but longer... without changing the information. Also you can use "brief and precise" in stead of "concise". This will not actually cost you a lot of time to read (2 extra words)... but it might save someone else 1 minute. Agreed. Yup. Read the above reaction. I just compare 2 articles with exactly the same info, one with simpler language which, I maintain, is possible. I think my point, together with many other's, is that we are researchers who are reading papers, and we aren't able to find the point of these papers easily, because we have trouble going through them because of the language, not the science in it. A paragraph ends with an empty line. I don't see any reason why digital papers in .pdf are contracted. they can do it for the paper versions as much as they like. I am pretty much at home with words in my own field, just having trouble with the most expensive Scrabble words in English which happens to be my 2nd language. Thanks, but if you're going to improve people's English here, you'd better quit your other job(s). The sms-language that is sometimes used on this forum is worse than mine... Although it can be argued that it is brief (and perhaps in a few lucky cases also precise). I think it's best to do both. I never read entire articles, but I browse them for data. I need numbers, because I am an engineer. Often 75% of an article is totally irrelevant to me. If abbreviations are hidden in that part, it takes a significant amount of time to dig them out. I'm fine with studying engineering, even other fields. I am just pretty bad at linguistics, and indeed, it's a matter of "Awww... but I don't wanna... I always hated to study other languages, which is indeed the reason I chose engineering as my field. I am glad we understand each other perfectly. It all comes down to having totally different expectations of papers, and also different reasons for reading them. You read them completely, I never do. You're probably a native English speaker, I am not. But I love the discussion. Apologies for length.

It took me several days to figure out that we're talking about Potential Energy ("PE") and Kinertic Energy ("KE"). I re-read the 1st post a couple of times, and every time I just clicked the "back" button after 3 seconds, because I cannot be bothered to think about abbreviations. Is it really such an effort to write out a few words??? Comon, lazy bums, press those keys on your keyboard... we're just typing, it's not calligraphy. People think it looks "scientific" to use abbreviations, I think it looks stupid, especially if you fail to explain them. On topic: Evaporation will cool the water. To my knowledge the falling doesn't heat up the body, it accelerates it. It's the friction that follows that heats the water. But since it comes to an almost complete stop at the base, we can say that it is converted to heat by friction almost completely. Sound is so marginal that I propose we neglect it. Evaporation is the only other parameter in the energy balance. Back-of-the-envelope calculation: Potential energy turns to kinetic energy, which turns to heat by friction: Height of Niagra Falls: 52 m. 1 kg of water has m*g*h = 1*9.81*52 = 510.1 J of potential energy. This is able to heat up the water by dT = Q / ( m * Cp ) = 510.1 / ( 1 * 4.2E3) = 0.12 degrees C... which is most certainly measurable. Evaporation: But, evaporation occurs. Let's look how much we need to completely negate this temperature increase (we'll need a couple of assumptions, because this is weather dependent): Assuming a temperature of 25 deg C. The vapor pressure of water is then: 23.76 mmHg, or (in real SI units) 3126 Pa. This means that 1 liter of air can contain n = PV/RT = 3126 (Pa) * 1E-3 (m3) / (8.3145 (J/kgK)* 298 (K) ) = 1.26E-3 mol of water, or 0.023 g of water (22.3E-6 kg). To evaporate this, it costs 51 J. So, to compensate the 510.1 J of kinetic energy, we need to saturate 9.93 liter of air. This means that if the air is totally dry (0% water), and the dispersion of water is 1 liter of water in 10.93 liters total (9.93 liter of air + 1 liter water) and the air is totally saturated at the base of the waterfall, then the temperature effect it 0. This also assumes that the air is refreshed all the time. Each liter of water falling needs 9.93 liters of fresh air. The volumetric flowrate of the waterfall is 5,720 m³/s (season dependent, I think). This means that the volumetric flowrate of (perfectly dry) air needs to be 56800 m3/s. The surface area of the waterfall is harder to estimate, because there is more than 1 actual water fall. The "horse shoe falls" are 792 m wide and 53 m high (why is wikipedia contradicting itself here? Earlier it was 52 m high). Anyway, this means that the frontal surface area is 41976 m2. Assuming a frontal wind, the wind speed must me 1.4 m/s, which is totally realistic. p.s. I was also assuming that the (cold) water doesn't cool down our nice and comfortable 25 deg C air. So, it is possible that you measure actual cooling in stead of heating despite the drop in potential energy. You can now grab your own calculators, and change some of my parameters to see the effect of higher AH, LT, LDoW on the FT.

Hehe, good one. New to me. To be honest, I haven't before seen the connection between the term exothermic and compression / expansion. It's usually used for chemical reactions. Since hell is probably a closed system, I'm sure it's adiabatic compression / expansion, which means that internally the temperature is going to change, but no heat will be absorbed or given off at all. I would have answered something related to the burning of the damned, which might in fact be endothermic because of the 70% water our bodies contain. but then again, I don't live in Washington, and I already got my degree so all crappy exams can go to hell and absorb or give off as much heat as they please.

Regarding math: it's not my strong point either. I'm a chemical engineer now, and I do have a very good feeling for my job, but as soon as differential equations or worse appear, I open some computer program, dump my problem there, and pray it works. Good thing that creativity is at least as important as math Regarding lectures at uni: I'm afraid that it's a fact of life that at university you will find lecturers who are totally uninspiring, boring, bad at explaining, and should never be allowed to teach... but because the good, socially capable and inspiring people left to industry/business they're the only ones left at the university, and they must teach. But it's not all bad... so keep your hopes up. If you complain as a student about bad teachers, you should consider a (part time) job as teacher when you're done with your studies. (Hehe, and I know every single student on earth complains about teachers)

Ok, then how do dictionaries explain these words? They too use simpler words... Or a synonym, which is, when you look it up, explained in simpler words. Synonyms in a (good) dictionary do not refer back and forth to each other, but eventually it is explained in simple language. Therefore it is now proven that it is possible to use simple language.

I agree with most points said earlier in this thread. I could start rambling about the papers I read (I hate them all for their language, I'm an engineer, not a student in English language). But my main point is: Concision (ffs, I had to Google that one, only 645,000 hits, which is nothing in Google) is a concept from the previous century when papers were printed and then shipped across the world in massive hardcover books. One year of a magazine could be 50 centimeters thick, printed on the thinnest paper available. Reducing length while keeping all information was a matter of money. These days, with youtube videos crisscrossing the web, who cares about a word extra? Honestly... we measure data in Terabytes now. So: -Make paragraphs. Scientific text has the longest paragraphs in the world, except for Franz Kafka who has created as many paragraphs as he has written books... -Use simple language, even if it means using 5 words in stead of 1. It's easier to read. -List things at the end: abbreviations, really difficult words (unavoidable), symbols.

hmm... I don't know the level of the bridging courses, but if they are given at the university where you also want to enter the science education, then I guess that they are indeed bridging. So, in that case my advise would be: take those bridging courses, give it all your best, and if you manage to finish them, enter the university. I hope that there is some way of having a backdoor exit without paying a full year of university in case you fail (which you, given the right motivation and effort, shouldn't)... but these are all questions you can ask at the university. Universities are bureaucracies, so it's going to take a little time to get through to the right person, but just allow yourself to spend a little too much on phonebills and get the info straight form the university. Preferably from the study advisor of the physics department, or a professor who gives the bridging courses. If they are not given at the same institute, try to connect them by (1) bringing books to the science university, and showing ("is this enough?") or (2) by trying to get the physics study advisor check whether they are good enough... Hopefully some Australian has some experience with this... it'll be more helpful than I can ever be

I like the SFN, but I absolutely hate facebook. Privacy is totally non-existent with the option for others to add information about you ("how do you know this person" and photo-tagging). In addition there is this Slashdot.org article which I found worrying: "Researchers at software vendor CA have discovered that social networking site Facebook is able to track the buying habits of its users on affiliated third-party sites even when they are logged out of their account or have opted out of its controversial 'Beacon' tracking service. [...]"

Same is happening in Scandinavia where people make routine visits to Estonia and Germany to buy cheap alcohol. Load up the car and go home to have a massive drinking party.

Good! Well, now everybody knows... and the world has become a little bit wiser.

I find the move that Georgia's president has made really stupid. Georgia has attacked Russian troops. Ok, these were on official Georgian territory, in Ossetia, but with Georgian consent. Russia responded by bringing more troops into Ossetia, crushing Georgian troops, and then continued their attack into undisputed sovereign Georgian territory. Russia already had loads of troops in the region (it's next door from Chechnya)... and the small Georgian army is no match. Now they have a war on their hands which they cannot win. Georgia was looking to the west, and that gets Europe and the USA involved. NATO is already stepping in, and telling nasty things to Russia. Russia has withdrawn its troops from a combined Russian/NATO exercise in the Baltic sea. NATO is now more strongly supporting Georgia which further offends Russia. Russia now refuses the US navy from accessing Kamchatka. Then to further light the fire, the Polish government has sealed a deal with the US army to build the rocket shield. I fear that the relations between East and West are going back to that of the 80's of the previous century. The war-rhetoric that I have heard from the US government really is totally stupid. The US has the attitude which says "Listen and Obey, We are Stronger than you...", which of course only offends the Russians. Finally the French president Sarkozy has reached a deal that the Russians will withdraw on Friday (with more smooth talks than the idiots in from the pentagon and US government) ... I really hope that they will listen, although I am afraid that Russian pride will prevent cooperation with European plans, because it also means agreeing to threats from the USA. People forget how nice it is to have open borders between east and west... crappy politicians only think about their own pride. source (unfortunately in Dutch): http://www.volkskrant.nl/buitenland/article1057569.ece/NAVO_waarschuwt_Moskou_krachtig http://www.depers.nl/buitenland/235667/Spanning-tussen-Moskou-en-NAVO.html http://www.depers.nl/buitenland/235661/Poolse-regering-keurt-raketdeal-goed.html [edit] Hmm, hadn't noticed the "Russian Tanks Enter S. Ossetia (Thread Separated)" thread, because I only did a search on "georgia" and checked the results with my eyes closed. I'm ok with adding this post to the end of that thread.

Makes sense to me. But then again, I live in a country where you can buy a beer at the age of 16, and strong alcohol (vodka and stuff) at 18... That means that you actually start drinking before you leave the house (of your parents) and move out to live on your own. It means that if you come home drunk, you're going to have to explain that. It means you learn to drink while being supervised The same goes for many European countries... And Europe is still doing fine I believe. So it cannot be all bad.

Betonite is the stuff that is used for kitty litter (you know, the grains that your cat will pee and poo on). Grind it into a powder and then re-shape it into a nozzle by applying enough pressure (a hammer in the hands of an enthusiastic rocket-builder will do).

Can we specify whether we're talking absolute numbers (that's mol%) or we're talking by weight (wt%)? Makes quite a difference. How certain are we of the composition of the core of the earth? Wikipedia uses the word "believed" when discussing the composition of the inner core.

I think Phi for All described the problem with solar power (and wind power) very well... Sustainable energy means that some companies will have less revenues. But then again, I've seen industries thriving while prices went down. Computers have become better and cheaper over the last years. In 1998 I bought my pc for almost twice the price as my latest computer... and that's despite 10 years of about 2-3% inflation. Phones too have become cheaper, and phone companies now even offer fixed line phone for free... Therefore I haven't lost all hope. It's true that energy companies would lose revenue from direct sales of electricity/gasoline... but they do have lots of expertise, and will be making money from us one way or another. I believe it's just a matter of conservatism and stubbornness that we're not converting a lot faster. Besides all that, I think that going off-grid is more expensive, because you'll need relatively lots of storage for energy. The bigger the grid, the less (relatively) storage you need.

Me too... but I was just talking about sand molds that are used for metal casting... But I just realized that you can cast something that becomes a solid without a temperature change... like a resin or gelatin. So, then you can actually use ice or something that would be totally useless for metal casting.

What is a cooling tower treatment? Is that just cleaning the inside of a cooling tower? What's the polluting substance inside? Are we talking about those massive 150 meter high cooling towers that are standing next to major chemical industry and power plants? If you want help from this forum, it helps to add more info! We're not "cooling tower water treatment experts", but we have the necessary scientific background and creativity in this forum to say something useful even if we're not experts... But for that we need a little introduction

You're going to do metal casting, and you want a mold that melts at less than 200 deg C? What kind of metal are you using? How does the casting process look? You got me puzzled I'll explain what puzzles me: I don't see the whole point of having a mold that melts, when the casting process is based on the principle of the mold having a higher melting point than the metal that you put into it. Sublimation temperatures seem even less relevant. In industry, sand is used for casting. You just pack it together, and put the metal in all places where you have no sand. You will need special sand for it because some sands can be shaped, while others (like beach sand) really are hopeless for this (look up the perfect mold-sand on google or wikipedia). Even Ferrari uses sand for casting their engine blocks!! (Like any other car manufacturer). Finally, if your shape is too complicated, you can create the shape you need out of polystyrene foam (styro foam) and pack the sand around that. Polystyrene melts at 90 deg C, but because it's so light its liquid volume is nothing compared to the solid foam. So, the hot metal will melt the foam, and immediately replace it, so the sand has no chance of collapsing. John Cuthber's idea of making a soluble mold might also work... although I think it's going to be tricky. The advantage is that you can wash it out... The sand will have to be knocked/shaken out.

I know that it's an average, and that there will be lots of particles that are smaller (and a few that are larger). That is also why I proposed a mesh of a bit less than half the size (which, I admit, was an arbitrary choice because I don't know the type of size distribution that would apply to this set of particles). the goal should be to filter out, say, 90% of the plastic. You cannot expect to clean it up completely. We'll have to wait until plastic-eating bacteria evolve for that to happen (I wonder which biologist will respond to this remark). I'm just trying to be positive, but it seems I still didn't feel like doing some simple calculations

Articles often say how models are more detailed, models are more accurate... I'd like to hear how stable these models are. If they also have a butterfly effect built in somewhere... I've made plenty of models (though none of the atmosphere) and sometimes a very small change in the model creates massive changes in results. Although I lack understanding of the models used, I suspect that researchers sometimes tweak the parameters that have uncertainty to create results that are more interesting to be published.

Is it going to be your first distillation ever? And you immediately try nitric acid? hmm... I really suggest that you do some practice experiments first. Try to concentrate your wine or something... Just to find out what can go wrong with the experiments, and to find out how stuff works. Hello ivy, Yes, we're all here! This is a forum, not a chat, so no worries if you don't get an immediate reponse. for saying hello, I can refer you to "The Official "Introduce Yourself" Thread"

That's another good suggestion Look up "boiling stones", and get some. Just normal sand will not really do the job (I tried that once).

According to wikipedia, you are boiling at 83 deg C... so I'd say normally a condensation at 10 deg C (tap water) is good enough... but it does sound like a particularly nasty reaction, with dangerous fumes (do this in a very well ventilated room!), so a decent cooling will make it safer. Ice + (lots of) salt can become quite cold. I get the feeling that nitric is doing this all at home, so dry ice in acetone is probably not available. Go with lots of ice from your freezer, and add a little water and lots of salt. Submerge the collection flask in that. Also try to connect the cooling (condenser) to some of this ice water. Experiment first with the cooling... and only then play with dangerous chemicals. Step 1 in distillation: test your setup!