CaptainPanic

With such assumptions (that sqrt(2) does not always have the same result) we can throw away everything that science has produced. There's no point in having such thoughts. It's fun, but it will lead (quite literally) to nothing. The way I see it: possibly some other reality exists... but I am quite certain that I am not inside that other reality, and therefore it's completely irrelevant.

What's a Ksp? I'm afraid I've never heard of this, but possibly you use a different abbreviation than me. It always helps to ask a clear question. We are maybe experts here, but if you explain to us all that you know, then we can better explain you what we know.

Who would have one what? One ice cream? In the end, Rocky wins. Please add an option "I just felt like voting" next time, for people like me... I just like to click teh buttonz

Your speed controller should be something of the type of a dead man's switch. If you fall, and let go of the controller, the engine(s) must stop immediately. I do not believe that this essential part is found on a radio speed controller... Please consider safety first, then practicality. As in the other thread - has anyone built anything so far? Anything at all???

Well, there you have it then. A car battery, two engines and a control system. In a shoe. On wheels. Guys, this isn't going anywhere... apologies for skepticism... Did any of the people posting in this thread make anything so far? Please post pictures. Perhaps we should close this thread.

No. I apologise for ranting without giving a definite answer, and I kindly request people who have an exact explanation to give it (and ignore me)... It's just frustration from my side. I have to work with this, and I have studied it in the past... To my knowledge, there are no standards for enzyme activity. There exist many definitions of units, and I believe that the most accepted unit, which is conveniently called "international unit", is denoted with the letter U (not: IU). The most likely translation of the U is [math]\mu mol ([/math]substrate consumed[math]) / min[/math], which would mean you have 5.1/60=0.085 µmol/(mg*s). But it can be something else... It can be product based (not reactant), it can be in /s (not /min) and whatever you're able to come up with. As an illustration, check out the unit "FPU", or "filter paper unit". This is also a "unit", and also for enzyme activity. And despite the fact that this unit has a different name than the other unit, it's still not clear what it means: (Reducing sugar?) Is that the same FPU as the first one? I doubt it. With bio-units, you never know... apologies for subjective remarks in a scientific thread. I have spent days, perhaps weeks, investigating simple things like this... and I'm sure that worldwide many people are suffering the same fate as vogelstrauss and me. But still nobody came up with the brilliant idea to actually just express enzyme activity in: [math]mol/g([/math]enzyme[math])s[/math] Anyway, the bottom line for me is that as a chemical engineer, I cannot work with publications from certain people because I don't understand it. However, when I work with people I know, then I can ask for a clarification, and without a problem, the activity is converted into SI - if it's so easy, why is SI not the standard?? [/rant without answer]

Correct. CH4 = methane. You have to combine the reactions so that you make the formation of methane form its elements. Then also recombine the heats of reactions to form the heat of formation. Study the term "activation energy" (hint: google/wikipedia). You don't need help with this one I hope. Just realize that "an experiment" is not necessarily 1 single reaction. You can do many reactions in 1 single experiment. Sounds good. We're not going to answer your homework questions - I've given some hints and hopefully you can solve your questions now. mod note: moved to HW help by swansont

What do you mean "self sustaining"? If you mean some device that boils water forever without requiring extra energy (so without the gas + air/oxygen as suggested) then forget it... that's just as impossible as a perpetual motion device. Perhaps you might want to rephrase your question.

You're one of those working people who is saving up all the holidays and will retire at the age of 63 (because you'll have saved up about two entire years of holidays)? My boss also loads me up with work, but luckily I know that people are pleased with my work, so I plan to just take my holidays this year: 4 weeks in the summer, plus one or two music festivals. Our P&O department says I'm allowed to take those days, so who wouldn't I? My work is research... this one month delay because of holiday isn't going to be the biggest delay in the research... and if I come back full of inspiration, I might save 1 month of work with just 1 brilliant thought - anything can happen Remember that "All work but no play makes Jack a dull boy". It's interesting to see the massive differences in holidays for school kids around the world... thanks for contributions so far.

Thanks for the link to wikipedia... cool to see that this compound exists, and nice to know the name: mesoxalic acid Glycerol, if clean, used to be quite valuable... but the reason people are interested to use it as a fuel is that the glycerol market has been ruined by the biodiesel producers who have loads of glycerol as a by-product. Glycerol is now almost worthless. Here's a list of "things you can do with crude glycerol (unpurified glycerol from biodiesel)" (warning: .PDF). Alternatively, you can add it to anaerobic digesters, (you also avoid the glycerol purification). The bacteria in those digesters don't mind some glycerol, and they'll produce methane with is a useful product. Still, we're talking about cheap fuels here, it's not exactly turning lead into gold yet.

Although this is interesting, reducing carbon dioxide is not the problem here... We should just stop emitting it. Preventing combustion (and subsequent emission) will always be more efficient than converting CO2 back into the fuel. Therefore, carbon dioxide reduction should come from clean sustainable fuels, which happens to be exactly what the world is aiming for: wind power, solar cells, (non-food) biomass and waste utilization. Only when the conversion of CO2 to methanol (or ethanol?) is solar powered (not electrolysis, but really like photosynthesis) and significantly more efficient than other processes to make a fuel, then I can see some merit.

Then how many holidays do school kids get in India? We got 6 weeks in summer, 2 weeks around Christmas, 1 week in autumn, 2 weeks in spring and a bunch of separate holidays. [edit] reposting my own post and a few previous posts for hijacking the "best moment today" thread with this school-holidays topic. Shall we move at least the last 3 posts (incl. this one) to "Science education"? [edit]thanks mods, for making a new thread of these posts.

It's true that you have nice protective stuff, but none of those mentioned help in case of an explosion. You're dealing with a potential detonation here, as you mentioned yourself - not just some spilled acid which can ruin your clothes.

Citric acid is [ce]C6H8O7[/ce], while glycerol goes by the formula of [ce]C3H8O3[/ce] Citric acid (wikipedia picture): Glycerol (wikipedia picture): On the glycerol molecule, you cannot completely oxidize all 3 -OH groups (to carboxyl), simply because the middle -OH group is attached to a carbon which itself is again attached to two carbons, and can only form a double bond at most with the oxygen (as in acetone). The most oxidized product of glycerol would be something like dicarboxy-formaldehyde, but I can't find anything about it, and I wouldn't be surprised if it is not stable and will instead form formaldehyde and 2 CO2. My first guess here is that glycerol doesn't want to oxidize any further without falling apart. But anyway, the reason we're investigating this (to lower the ignition point through oxidation) is nonsense. You shouldn't be partially oxidizing a fuel. It lowers the heat of combustion. And the use of small molecules, as mentioned before, is not going to make a gel. So, unless we think this is more interesting, we should return to the original topic, which is either: "how to make a fuel gel", or "how to use glycerol as a fuel"? 1. how to make a fuel gel? - Already answered: get a crosslinked polymer in sufficiently high concentrations. 2. how to use glycerol as a fuel? - I found that glycerine acetate is a fuel additive. - Alternatively, you might have to remove the -OH groups (hydrotreating or hydrocracking or something - not sure it's worth the effort, and apart from the fact that probably none of us have the right catalysts, it is surely not something you want to try at home).

I also think it's possible. The number of 10^47 J is so immense that it should be possible. Earth is 5.976*10^24 kg. Heat it all up by 5000 degrees, using the CP of water: 21*10^6 J/kg. And to evaporate it another 2.3*10^6 J. Total energy required according to this estimate: 1.4*10^32 J... (which less than a factor 2 different from the value above, and I've given some argumentation for the number, which I couldn't find on the link provided). In short: 10^47 J is about 1000000000000000x too much energy, and I wouldn't be surprised if you can destroy a star with it, not just a planet.

Imagine a SETI program on a planet at 4 light years away (nearest star system from us). What can you pick up from earth? We're broadcasting countless simultaneous things on the same frequencies (how many FM radio channels exist that broadcast on 92.4 FM (39000 hits in google), how many phones are in the same frequency, how many TV stations)? While these signals are located on different places on earth, and don't seem to interfere with each other here (because one source is much stronger than the other), at 4 light years, the different locations on earth are no longer of any significance, and all signals seem to originate from one source (the tiny dot called "Earth"). Would it be possible to single out a message, or would it all be signal noise due to the other signals on the same frequencies? And how strong would the strongest signal be at such distance? Does our magnetosphere also disturb the signals? I realize that some signals are more powerful than others. Lots of questions that all came up when I posted a remark about another newly discovered planet. I was wondering if it's likely that SETI picks up any signal from such a planet even if it would be as advanced as Earth.

Seems like an interesting system. We should prepare the galactic battleships and invade! [brainstorm]Does anyone know if efforts are made to zoom in on a single planet or star system by SETI to carefully check it for weak signals (like the ones we make here: local radio, telephone etc)? SETI is now just listening to the entire universe, and it seems to be hoping for some lifeform that has decided to blast some data into the universe. If we know some likely place for life to develop, then we can zoom in, and maybe pick up more faint signals too?[/brainstorm]

Would you mind giving us a link to the error? The start of the page about the Reynolds number (Re) seems fine. I did find a part called "Where does it come from" (same wikipedia page). Could you point out where you have a problem? The formulas are not the same as in my book, and the whole trick with making the entire Navier-Stokes equation dimensionless and then changing some stuff about it is unknown to me. However, when checking the top and bottom formula of the "where does it come from" section, I find it weird that the [math]-\nabla{p}[/math] term is not changed, while all other terms seem to lose the density [math]\rho[/math]. Dimensionless these kinds of tricks might be acceptable, but once the primes are dropped (for ease of reading? what kind of reason is that?), the dimensions don't seem to match anymore. Regarding some "S" number, all I know are the Schmidt (Sc), Sherwood (Sh) and Stanton (St) numbers...

The kids don't seem to realize that a 35 hrs work-week, 12 weeks of holiday, zero responsibility and a large group of friends as colleagues isn't really bad... in fact: it's pretty good. Anyway, my best part of the day was to hide in a very quiet corner of the library of a neighboring company where a friend works. I was certainly not going to be disturbed by emails/colleagues and also wouldn't be distracted by any other entertainment. I went through a mountain of boring (but important, work-related) papers. Walked back into my office at 16:00. I did work in 1 afternoon what would have taken me more than an entire day normally. It's so great when you can finish the boring stuff so quickly.

The kids don't seem to realize that a 35 hrs work-week, 12 weeks of holiday, zero responsibility and a large group of friends as colleagues isn't really bad... in fact: it's pretty good. Anyway, my best part of the day was to hide in a very quiet corner of the library of a neighboring company where a friend works. I was certainly not going to be disturbed by emails/colleagues and also wouldn't be distracted by any other entertainment. I went through a mountain of boring (but important, work-related) papers. Walked back into my office at 16:00. I did work in 1 afternoon what would have taken me more than an entire day normally. It's so great when you can finish the boring stuff so quickly.

Although I don't agree with the described behaviour of the neighbors, I am not sure exactly where to draw the line. Keeping the cat inside is definitely an option, but I know plenty of cat-lovers who will find this unacceptable. It can be hard to reason with animal-lovers sometimes Just playing the devil's advocate here: In the Netherlands, we have really lots of birds. Sea gulls can really shit a lot, and during the breeding season actually dive-bomb people and also have fun to aim for the windows. Sea gulls are nesting on the roofs of buildings, where the natural predators (fox, cat, other small egg-eaters) cannot come. Is it the responsibility of the owners of the buildings to keep the sea gulls off? I think not. Sometimes you have to accept that nature just makes a mess. Note that a pet cat is not exactly nature anymore, and I think it is the cat's owners responsibility to prevent it from shitting in the gardens.

Depending on the cat, it's important that the cat does not see you when it's hit with water from the super soaker. You want the cat to associate the water with the garden, not with you in person. A smart cat will quickly understand that the toilet is open and safe when you're not in the garden. This automatic sprinkler installation - will it not also chase all birds and other life away? (Or, alternatively, isn't it going to be triggered all the time, by wind, cats, birds, yourself if you forget to turn it off, etc.?)

There's a difference between immigration (for work and permanent residence) and travel for holiday purposes. Lots of people from outside the EU can visit, although this is mostly determined by the average income in the other country and also by politics. Basically, if you come from a country from which many people want to immigrate, then that's bad luck and it's difficult to get in... I think that the second point is a good one. The terrorist groups in Europe seem to have plenty of weapons... so yeah, I may have to take back my previous statement... although I hope that groups like the IRA and ETA do not have 29000 guns, because then they might actually outnumber the armies of the smaller member states of the EU...

In most European countries, there is a free traffic of people, but almost no (illegal) guns. I'm not saying that our system is perfect, but it might just be an example. Of course, it would be nothing short of a revolution in the USA: we have heavy restrictions on gun possession, which seems a big no-no on the other side of the Atlantic... Thanks for that. For me it's not a "no-brainer". I honestly have never held a gun in my hand. I didn't know they have a serial number. I didn't know that there's a computer system for it. (Possibly I have heard about it before, but I don't just believe anything I hear from Hollywood).

Same stupid mistake as the Germans in WWII. If you're going to commit crimes against humanity, don't write about it in official documents. How is it possible that this kind of info leaked? Apparently it's easier to extract the truth from a torturing government than from a terrorist. All jokes aside, I believe that waterboarding is a crime against humanity. It's real torture (the number 183 is irrelevant, just 1 time is enough). Just 8 years ago I would never have believed that such a thing could happen in a Western democracy.