CaptainPanic

Good post. That's what engineers like: just a simple description of what needs to be done. This removes some unnecessary boundary conditions, and makes it possible to "think outside the box". So, the main question is: what is the main goal of the project? To build the submersible? Or to get footage from the bottom of that lake? From your last post, I conclude that the goal is to make a video of the monsters of the deep in Lake Superior. First of all, I really don't see the point of trying to make a submersible that is autonomous for this task... The practical problems are numerous (battery life to get 40 miles from the shore is already an issue - the buoyancy, the control systems, the balancing... you're looking at years of development probably). I'll just tell you what I would do: You need to get a camera and a lamp to about 400 meter deep, and 60 kilometers (40 miles) off shore into a fresh water lake. The lake, according to youtube fishing videos is safe for relatively small boats (on a calm day)... I'd advise to just waterproof the video camera and the lamp. To attach them to a rope. Attach some weight (a brick). Sink it from a boat into the lake, straight down). Get the video. Pull it back up. Move the boat. Repeat. Getting a video camera which is waterproof for 40 bars of water should be your only concern... and frankly, I would just buy one. That's so much easier than waterproofing a regular camera yourself. I'm really sorry that I write absolutely nothing at all that involves any tinkering in the garage, playing with glue, soldering parts... I advise you to buy a camera. Add some weight... get a boat... and start filming. I think it's much more realistic than building an autonomous submersible camera to investigate the largest lake in the world.

Why do we laugh? What's the evolutionary point of it? Ok... let me answer the most basic part first: it's a part of our communications, and therefore quite useful. Something unexpected happens that is quite harmless (not dangerous) then there's a good chance that we laugh. If that unexpected event links back to something that happened in the past or has otherwise some meaning to the us, it's likely that we'll be roaring with laughter. It's even funnier then. That's a useful communication to explain a rather complicated concept very quickly. But what is the point of just rolling on the floor laughing, almost completely incapacitated by laughter, tears in our eyes and all? If I try to think of human evolution, I think of a bunch of cavemen. And I cannot imagine a bunch of cavemen having any benefit from laughing. It makes noise. It distracts any guarding cavemen (they also want to know what's so funny, and will consider to leave their posts). It does not produce food. Yes, it creates a group feeling, but other animals don't need laughter to form cohesive groups. The only thing I can come up with is that it's well-known that women like funny men, and men like funny women. Are jokes our peacock-feathers? Pointless for all survival, but awesome for getting laid? Or is there another good reason?

Took one direct hit... but I disagree with it. Anyway, it's a funny exercise

Says who? Muslim fundamentalists have a hatred of anything and anyone who doesn't accept their rules. They just as happily attack Mumbai (which is in India, and has a largely Hindu population). Most victims of the Muslim fundamentalists are their own countrymen and women, who are Muslims. Honestly... I strongly believe that it's a complete myth that Muslims have something against us. I am afraid that the opposite is true: a large group (right wing) in the Western world has something against Islam... and therefore they spread these stories. And the people who really have something against us have something against almost everybody. The world needed an enemy after the Commies were defeated. And after searching long and hard, someone found some fundamentalists who said that everything was evil. That was twisted into "The West is Evil"... and Voila... we have a new enemy. ------------- On a sidenote, related to the Israel/Palestine problem... here's why it's great to be Dutch. Nobody claims that our land was theirs... because we made it ourselves, and we have the to prove it. ------------- ... But let this intermezzo not distract you from the main topic, which is why we seem to believe that Muslims all hate us, and why that thought makes us all hate Muslims, and/or who is the real owner of the ground which we now call Israel and Palestine.

Make sure to inform the neighbours that their house garden or entire street may soon disappear into a big hole or a cave-in, and/or that all the groundwater will be pumped into the nearest drainage by your pumps that keep your hole free of water. As for the rest... Good luck. Call me a conservative engineer... but the way you present your plans makes me think that the chance that you kill yourself while making your bomb shelter is much larger than the chance that WWIII will happen in your lifetime.

I've read that the area that flooded is the size of France and Germany together... hard to believe that in an area that is more famous for droughts there is such a massive flood. Good luck to all those who are in that area.

Please Google for [candle burning blue flame]... In my search results, the 1st hit sells candles with flames in several colors. The 7th hit gives the explanation. Explanation here.

PLC training certainly is useful for the automation of the production of pink bunny rabbits. Can we close the thread now? The links have already been sabotaged by a diligent moderator.

Let me start (I hope you don't consider this a flame) that you expect us to solve a practical problem of a jet engine, but you give very limited information. Why don't you take a little bit of time, and provide us with real information? A proper description of all components of the engine, preferably with diagrams. Since it's a pulse engine, we also need to know what is happening at what time. Pictures might help too if we can see something on it. My only conclusion is that something is broken... and that "something" hasn't been described yet by you. Fuel inlet is functioning normally? Fuel is getting distributed normally? I guess it is sprayed somehow? In the right direction? The synchronization of the fuel inlet and the air-valve works?

If you just want to keep something warm for as long as possible, while also getting warmth from it (for your cold feet), then I'm afraid that there are hardly any alternatives for water. Water is already quite awesome... it's just so common that we forget. The sodium acetate pads won't do anything while the water is still warm... as sodium acetate just doesn't crystallize then... And when the water is cooling down, you want to be asleep already... but the sodium acetate pads need activation (there's often a little metal click-thingy in it which will start the crystallization process). I'm afraid that in your case, the simple and boring solution is: use a regular hot water bottle, and bigger is better. Twice the volume of water holds twice the heat. If you use a regular bottle now, and you upgrade to a bottle twice the volume, it will stay hot for a longer period. That's because the surface area increases (relatively) less than the volume as you take a larger bottle. Alternatively, you can take two similar bottles, and insulate them a bit. Then you also increase the heat by two, and the added insulation (a cloth) will reduce the heat you get from it. The net effect is that you get the same heat as before from one bottle (but now from two), and it takes longer to cool down. I'm just being pragmatic here... if you prefer to discuss the reactions and chemically interesting options, just say so.

I agree that that's the best thing to do. Pity that most acts of terror are called terrorism well before the official investigation is over. The initial choice of words in the media usually sticks. And the initial choice of words in the media is undeniably heavily biased. White 22-year-old college kids just don't do terrorism...

My advice to Lekgolo555 is to combine exercise with useful things. Cycling or walking to work, friends or the shops is great, and costs very little extra time (since you'd otherwise be waiting for a delayed bus, standing in a traffic jam, or circling around searching for a parking spot). That removes the excuse that exercise costs too much time. For me (lazy), exercise is a matter of removing enough excuses until I do it. I agree with you that 2 minutes sounds long for almost any exercise - except cycling. My experience when cycling is that, indeed, the first kilometer or so, my breathing is significantly slower than the rest of the trip (although I don't hold my breath - I'm quite fond of breathing)... That period can easily be as much as 2 minutes. It's at this point worth mentioning that I do relatively serious cycling, and usually try to keep a constant speed through the whole trip. Could it be that (1) cycling is mostly done by muscles in the legs which are big and can store more oxygen, ATP's, or whatever is needed (notice that I just cycle a lot, but know little about our metabolism), or (2) that the reason is that unlike running, the breathing does not need to synchronize with the movement of the legs because you're essentially sitting or (3) because in cycling you have gears and you can therefore optimize which muscles you use? I'll expand a bit on (3) because I think it comes closest to making sense (but who am I to say that). I heard that we humans have broadly speaking 2 types of muscles: for explosive actions and for endurance activities. With running, although it is endurance, you also have some more explosive actions (parts of each step are like a jump). With cycling, the movements are much less sudden, especially when you choose a gear that you like, and therefore breathing may not have to go up so fast? But then again - there's a reason I hardly ever post on the medical science forum, and lots on the engineering forum. Looking forward to hear if this post made any sense. There is only one massive problem with the diet you advise, and that is that it involves drinking less beer.

the following might be considered an opinion, and I am not going to bother to back it up with links and sources. (Sorry). The Western world is doing everything to keep the 3rd world poor. We give huge amounts of money to the 3rd world, which they have to pay back with interest (so they pay more to us than we give to them). As any creditcard holder knows, borrowing money costs money. We don't mind to sell weapons. In fact, all conflicts in Africa are fought with weapons manufactured outside that continent. Western countries do nothing to support a local economy in 3rd world countries. We have import taxes for cheap agricultural goods to make our own farmers competitive. We dump agricultural products from the west in the 3rd world countries, and even compensate our own farmers for the lower price they get in those countries. We allow companies to employ people in poor countries under their own unhealthy badly paid labor agreements... heck, we act as if it's a healthy and understandable practice when companies move oversees to "cheap labor countries" or whatever euphemism they use for "producing the same as before, but spending a lot less on the people who do the work". And we get cheap goods, and we buy it... and we're even arrogant enough to say that we help the poor countries. Africans don't own Africa. Other people do. Logically (or at least, we say that it's logical), the profits go to the "owners". Up until a few years ago, Western countries owned most of Africa. Only recently, China started to invest. China itself only escaped this fate recently because they're their own owners. Former colonies became independent only in name. Western countries once really owned them... now we just own the economy.

What an impertinent thing to say. Terrorism is defined by the motives of the perpetrator, not the religion one subscribes to. To say such a thing seems to promote stereotyping and the rhetoric issue raised by the op. Your comments seem to confirm the concerns expressed in tis thread. I realize that later in the thread, you (sort of) finished and concluded this already... However, I thought it might be interesting to add this: There is a case of prior art... although not in the USA. In the Netherlands, a man, acting alone, killed someone. The motive was clear (hatred against the victim), although the victim in the Dutch case was a film director, not a politician. The victim and the murderer had never met before, and had no personal relation. The murderer was connected to others who shared his opinions and who said to have similar plans (although it was just words, certainly up to the moment of the murder). The murder took place in a public place, in daylight. Contrary to the case of Giffords, there were no other victims. As you can see in this link (wikipedia), the Dutch case is linked strongly to terrorism... The main difference, apart from the ones I mentioned above, is that the murderer in the Dutch case was a fundamentalist Muslim... and in the American case it was a white college student. I have to concluce that I definitely think that ydoaPs has a point - unfortunately.

You only need to add as much energy to the water as you will lose from it to keep the temperature constant. I continue the post below assuming that you want to have a hot water bottle that stays hot longer (for heating your cold feet in the bed for example). If you want to increase the specific heat of water, there is nothing practical that can do that. Water has an incredibly high heat capacity already... so if you want to pack as much heat into a liter as possible: go for water - just plain ordinary water. However, cypress made a good point saying that there are safe materials that will actually undergo a phase change (like freezing) or a reaction (crystallization in cypress' example)... and those will have more joules per kg of material than water (or at least I believe so - can't find the numbers so soon). Your question however was a little unclear.

Smoke from a jet engine suggests incomplete combustion, which, as insane_alien mentioned, suggests that something is broken. I agree that we don't have enough information... But it took me about 10 seconds to find a RC (remote control) Jet Engine forum - maybe those experts can directly point out a very common failure. Good luck.

I'm afraid that the title does not say it all... In case you're talking about a heater for something (even that's not completely clear), you also have to tell us: - what material are we talking about - what temperature does it start at - what's the purpose (any practical things you need solved, or do you just want the most basic formula?) Your question doesn't have an answer I'm afraid... but a quick google search got me some heater calculators for water.

I'm no expert... But I believe that your first paragraph at least is quite right. Personally (this may be called speculation) I believe that scientists cannot prove that the universe was at some point at infinite density in an infinitely small volume (zero volume). What scientists can say however is that they can calculate back and also observe that the universe was a lot smaller earlier on. And even smaller before that. And then even smaller and denser before that. And before even that, we don't know (only models exist, but no measurements or observations)... but a little extrapolation suggests that it all came from a single point... which then logically should have infinite density. I believe that there is no solid evidence for the first bit of time after the actual Big Bang. Scientists have been able to build a model which can calculate back what the universe could have looked like (and should have looked like if our laws of physics are true)... But the oldest direct measurement is from the Cosmic background radiation... and then the universe was already 380,000 years old.

If I may... I believe that the answer is given on the Wikipedia website about Saturn... and specifically in the paragraph that deals with the atmosphere of Saturn.

Maybe it would be wise to tell us what you want. The shape of the flame. How long it must burn. Why you insist on a kevlar wick. Why blue is the only possible color for you. A regular bunsen burner, when it's oxygen-rich burns blue. Blue fireworks are, as you already mentioned, done with copper components. Fireworks may burn or explode a little too fast for you though. I don't know how clean kevlar will burn (or why you would want to use it)... it may create soot, and therefore be orange/yellow.

Is that why governments are kindly requesting Internet Service Providers (private companies) to block content, rather than doing it themselves?

Freedom of speech is explained by some people as "I can say whatever the hell I want, whenever, wherever"... which is just silly. There are a lot of things that you shouldn't say, because the other person or group just doesn't like it... For example, I can think that my boss is not functioning. As long as I keep that to myself, it's fine. As soon as I say it in public (behind his back), I can jeopardize my career. And if I say it to him in his face, without the necessary politeness and without backing up my point, I might as well be fired... and if I would call anyone in our company names, then I lose my job instantly. It's just not done. People who explain the "freedom of speech" as the "freedom to insult" just haven't understood it. If you call someone an a**hole on the street, and you get into trouble because of that, you have yourself to blame... not the other person because he doesn't respect your freedom of speech. If you call someone else's mother a b*tch, you will again have yourself to blame for the trouble you find yourself in.

Actually, it's carbon itself that makes red/orange/yellow colors in candles and fire.

If no force acts on an object, what does it do? Today's choices are: A. Travel in a straight line. B. Stop instantly, while waiting for further instructions. C. Do a funny dance I think you can answer this one yourself.

Other materials in your fire staff will give off a color as well. If that's wood, candle wax or something else that burns distinctly orange, then you will at best get a mixture of blue and orange.