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John Cuthber

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Everything posted by John Cuthber

  1. "would the shiny side of tin foil work? " Yes.
  2. You could measure the aluminium and work out how much sulphate the aluminium sulphate contributed. A titration using a pH meter as the "indicator" would, I think, give breakpoints corresponding to the titre of H2SO4, HSO4 and Al+++ so that would give quite a lot of information.
  3. Heat gets transfered by convection, conduction and radiation. The first 2 need something to carry the heat so if you can trap a layer of vacuum (OK, I know that's an odd way of putting it) around the thing you want to keep cool you wil prevent heat reacching it by convection and conduction- that only leaves radiation to carry heat to the ice. If you wrap a mirror round it the radiant heat will be reflected away. You might want to look at the wiki article on vacuum flasks. OTOH, I don't think you are going to build a vacuum flask as a school project so I would concentrate on good insulation. I guess that insolent stuff is some sort of aerosol can full of foam. If so it's probably very good for this sort of thing. A couple of boxes, one inside the other and with the gap between them filled with foam (styrofoam works too) would be a very good start. (You need a "foam" lid too- obviously).
  4. If this http://www.detectors.saint-gobain.com/Media/Documents/S0000000000000001004/SGC_SodiumIodideDataSheet_1005.pdf is typical (and I think it is) then the problem with NaI is that it emits lighht at about 415nm, that's only just visible so the eye won't be very sensitive to it. Even to get that you need to dope the NaI with thalium and that's not stuff you want to play with.
  5. I'd really recommend that you look at some other metals too. Some small iron nails might be a good idea. Since it's a school science project you could ask them for advice on getting some other metals to try- zinc would be next on my list. It might also be interesting to try other drinks etc. I'm not sure I know anyone who drinks neat lemon juice, but I think it might give an interesting result. I will let you decide what your parents / school would think about wine and beer, but it would be perfectly valid science to test them too. A possible compromise would be to use low alcohol versions.
  6. A blade is a good thing if it is a surgeon's scalpel and a bad thing if it is a murderer's dagger. There's nothing new about the fact that new discoveries can be used for good or bad things. Societies generally enact laws to prohibit daggers and permit scalpels. The same thing will happen with this technology.
  7. It's OK, nobody ever looks at stuff posted on the net. You are just as safe as the person who posted about getting away with murder.
  8. I don't seem to be the only one who thinks autocorrelation is a test for randomness. http://www.itl.nist.gov/div898/handbook/eda/section3/autocopl.htm You seem to have forgotten that what I originally wrote was "And, at the risk of arguing against myself, pi is random in a rather obscure sense. " Did you miss the last clause there? You wrote "I fail to see the distinction between a "clear" pattern and "no clear pattern". " Apparently, however many of us would see them as distinct. And you wrote "Making a new word and using it as an already existing work is bad for clarity." I presume that I shouldn't use the word random for anything non random. The trouble is that (arguably) nothing is random. "Pi has not been calculated, nor has it been proven to be infinite" True, three and a bit hasn't been proved to be infinite; probably because, since it's less than 4, it is clearly finite. It has been (I understand) proved to be transcendental so its decimal (or any other rational base) expansion is infinite. The proof is effectively the same as the impossibillity of squaring the circle. http://en.wikipedia.org/wiki/Squaring_the_circle From that I deduce that if you are looking for any finite series of digits in pi and you don't find it, it's because you have not finished looking yet. You asked "how do you know it simply doesn't go 77777777 at some point, having a finite number of fours?" I'm perfectly certain that it does go 77777777, not just at some point, but at an infinite number of points. It also has an infinite number of 4s (but not an infinite sequence of 4s because, to be infinite that bunch of 4s would need to be at the end, which would make pi rational which it isn't). At the risk of being really petty I should probably point out that you wrote "The first 4 will ALWAYS be followed by 1." and you objected to one of my comments because it would only be true in base 10. Dear Pot, thank you for you comment, best wishes Kettle. And btw, strictly, what I wrote would also be true in any finite, integer, base greater than 10. Personally, I like numerology; it's one of my favourite jokes. Anyway, the original posting 's idea sucks for any or all of the reasons put forward.
  9. I'd start by thinking about how heat is transfered and what I could do to stop it.
  10. Is it just me or does the idea that "I don't think the tendancy for scientists to lean towards the left has ANYTHING to due with natural philosophy. Simply stated, the left seems to put a lot more funding into non-military research than the right." misses the point that the right wing put a lot more money into research (military research) than the left wing puts into any research. If, as a scientist, I just want a government that spends lots on research, my best bet is to vote for the right wing and get a job working in military research. This could be taken as evidence that scientists are even more left wing than they look but some of us have been "paid off" by military research work. Personally I understand the efficiency of a free market for goods; Adam Smith worked out the basics of it a long time ago. However, being quite clever- which may be related to the fact that I'm a scientist or it may not, I can also see that, for example the care of the mentally ill is not something that the market can be expected to do well. There are other things (I gather the economists call them "public goods") which capitalism simply can't handle properly. That's why I'm not rabidly left wing or right wing; it's why I can take some sort of place in a debate on the matter, and it's also why I can see fault in either side getting too powerful- total freedom can be freedom to oppress
  11. Just a thought, There's no question that there are differences between "black people" and "white people" whatever those terms mean. There is a question over the idea that one group (no matter how it is defined) is "superior" to another group. In my (undoccumented, unscientific and limited) experience ,colour of skin is a rather poor predictor of general inteligence however racist beliefs seem to be negatively correlated with inteligence.
  12. I just wondered if liver with Chianti counts as meat and acid; but that's probably just my weird way of thinking.
  13. Just for the record, while it may be a usable source, it may not be a legal one. Anyway to answer the original question, no. Sorry but you need carefully processed and doped ZnS to get a decent effect. I have seen the light from a beta source irradiating a bit of the phosphor covered inside of a broken fluorescent tube, but I can't say I recommend this experiment.
  14. Actually, I guess it depends on what you mean by "represents". Here in the UK about 9.5 g of some brassy alloy represents a pound. I think the question refers to the fact that, seeing that title, we all want to prove just how smart we are so we answer a question that might otherwise seem too trivial to bother with.
  15. John Cuthber


    Offhand, I can't think of any biological system that isn't buffered, possibly stomach contents which are strongly acid. Tears, blood, milk etc are all buffered.
  16. You forgot e) the perpetrator had to leave a hair behind because it's in the script. Don't get me wrong, I enjoy the show, but I don't think of it as a documentary.
  17. The fact that you don't have enough data to tell what follows "3" is precisely what makes it "random". It would be perfectly possible to generate a transcendental number that never included, for example, 3. "With enough info one can determine where you are in the string and start predicting with 100% accuracy." No, you cannot because any finite sting of digits will occur in the decimal expansion of pi an infinite number of times and will be followed by each of the digits 0 to 9 (an infinite number of times for each digit). How often each digit will follow the sequence is "random" in that is unbiased in the long run. I accept that it's perfectly possible to calculate out pi to as many places as you need so it's perfectly deterministic. However, if you did generate the sequence of "digits that follow 4s in pi" it would look just like tossing a 10 sided dice; there's no pattern to it. If you did the same thing with the decimal expansion of 1/23 you would get a very clear pattern. 4 is always followed by a 3 or a 7. That's the only sense in which pi is "random" and, in refutation of the original post, it has been shown to stay "random" for a lot more than 121 digits. I have a vague feeling here that what is in question is the meaning of random, I think the one that makes pi look random is a lack of auto-correlation. Of course, since I can always calculate the next digit it isn't random at all and that's the point I made originally because it seem to rather pull the rug from under the original post.
  18. I'm not sure if this is chemistry; it's an odd question but I think that fact that fats do not dissolve very well in acids might help. I think chicken is usually less fatty than beef; I'm a lot less sure about "fish" because there are so many types. At least some fish are known as "fatty fish" when talking about omega-3 fatty acids so I guess they are more fatty than chicken. I also think the fats will get in the way of the acid. If all that is correct and there isn't some other confounding factor I have missed out then the chicken should dissolve fastest.
  19. Well you have got as far as the ratio of Na to acetate must be 1 to 1. What is that ratio now and what would you need to do to make it 1 to 1?
  20. Err, I think "Pi in base Pi is 10. " is misleading. Non- integer bases run into problems. In base 10 I can use all the digits 0 to 9; there's no need for anything bigger than 9. In binary I only have 1 and 0. What digits can I use in base 0.5 ? And, at the risk of arguing against myself, pi is random in a rather obscure sense. Given that a particular digit is, for example, 3 does not give any indication of what the next digit is. Similarly the sequence of digits 25356 is just as likely to be followed by any digit as any other. It is, in fact, used in random number generation and, as such, it was tested for randomness (of this type) a long time ago to a lot of digits. It passed so there's not going to be anything interesting in the first couple of hundred digits. http://news.uns.purdue.edu/html4ever/2005/050426.Fischbach.pi.html
  21. You should look into following your doctor's advice.
  22. Pi can be calculated, if you tell me what digit you want, I can (in principle) tell you what it is. It's not random. The 3rd digit of pi (in denary) is always going to be 4. Nothing random about it and the same goes for any other digit in any base. You cannot have a changing value of the radius of the universe if it is calculated from a collection of constants (Planck's constant and some parameter calculated from the (randomness of the) digits of pi). Whenever you calculate it it will give the same answer. 6 times 7 will still be 42 in 13.7 billion years and it was just the same as close back to the big bang as you like. Whather or not pi was still about 3 before the big bang is a matter of philosphy and I'm not sure the question has a meaning. If you take the view that maths was discovered (ie like America, it was already there for Columbus (or whoever) to find) then pi was 3 and a bit before anyone anyone noticed it and it will still be 3 and a bit forever. Since as you say, the radius is changing, there is a problem with your theory.
  23. "yeah, thats right eg. cis-2-chloroethene or trans-2-chloroethene" Err, that's a rather poor example. In one case the chlorine is cis to a hydrogen and trans to the other one. In the other case the Cl is trans to a hydrogen and cis to the other. There's only one isomer. For what it's worth that compound is 1 chloroethene rather than 2chloroethene Anyway, the answer seems to depend who you ask but, for example, names like "cis,cis,cis,trans-[]-fenestrane" can be found on the 'net. Here are the "official" rules from people who can't spell sulphur http://www.acdlabs.com/iupac/nomenclature/
  24. I'm puzzled, why don't you think the reaction has gone to completion? Since adding more eggshells doesn't produce more CO2 I think the acid has been used up. Btw, please give me the names of insoluble acetates that could plausible be present.
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