mezarashi

Well your idea is great. It's probably what most engineers would have in mind. The propulsion is not so big the issue. The main obstacle for commercializing this is the amount of material needed for magnetic levitation; it's not economical to say the least. The second obstacle is stability. Have you ever been able to have one magnet levitate over another just right? Imagine a train on such tracks. One little shake and it slips off just like that. You will need to devise a very complicated control feedback scheme with low response time and minimal overshoot, since overshooting can cause it to slip off the other direction. Although I am confident in our current control technology, the amount of material needed doesn't explain itself.

I'm sure this will be easy if you have the equations clarified: 1. tangential acceleration = change in angular velocity over time (hint: slopes of the graph) 2. radial acceleration = (angular velocity)^2 x radius (hint: since r is constant its proportional to the square of the angular velocity) Lastly, total acceleration = radial acceleration (towards center) + tangential acceleration (tangent to rim). (hint: last question, if either is non-zero, you won't get a perfect radial or tangential vector)

I've seen this one before. The phenomenon is probably known better from smoke-rings. If you know someone who smokes you've probably seen the same happen with the loops of smoke as they continue to pass each other. In science these are called vortices or vortex rings in this case. The interaction between the vortices allows for such to happen. The exact physics behind it is too daunting for the likes of me. The phenomenon was first noticed by Thomson and Helmholtz (I think you know their names), and considering that Maxwell also stepped into the picture of this problem, I think I better leave it at that ^^

You should have convered: d/dx ( exp(ax) ) = a exp(ax)' date=' where a is a constant. Now let a = -1. (-1)^n alternates between positive and negative for increasing integer values of n.

Anywhere you find time-dependent electric fields, you will most definitely find magnetic fields. So if those electric signals exist, then most definitely your brain will produce magnetic signals as well.

Right off, I disagree with your g'(x). Refer to what i said about the derivative of exp(-x). Edit: or what dave just posted right now

Since temperature increases pressure in a fixed volume, it would make sense in that respect. I just hope that it is understood by AgenO however that the internal kinetic energy of any gas is not related to any net drift phenomena. My concern here comes from his first post questioning What the temperature can do is affect things like pressure and air density which will result in convection or winds.

Don't just assume that. The derivative of exp(-x) is -exp(-x). Notice that to differentiate g(x) = xexp(-x) you will need to use the product rule. Using that, write out: g'(x) g''(x) g'''(x) and so on. Enough so that you see a pattern. For example if I had the function f(x) = exp(ax) Then f'(x) = a exp(ax) f''(x) = a^2 exp(ax) f'''(x) = a^3 exp(ax) I can conclude that f(n)(x) = a^n exp(ax). Got it?

Honestly, I think you need a professional editor. 50-60 pages. Unless you really have a good friend, most people would charge for that.

If your final answers are correct, shouldn't that be in itself a good check?

w00ts alright! Thanks. A bit trickier than I thought... but the text assumes its fundamental =/

Half-way through some derivations and I find that I come across an elementary mathematical operation that I embarassingly don't understand. Somehow it seems to have eluded me. The jump from 1 to 2 is: [MATH]z = \sqrt{jA^2}[/MATH] [MATH]z = \sqrt{j}A[/MATH] [MATH]z = \frac{1}{\sqrt{2}} A (1 + j)[/MATH] j indicates the imaginary number. I'm not sure how the square root j was expanded there. Would anybody please explain the idea behind this? Any other generalities to look out for?

I have this problem too especially when the text is rigorously mathematical. As you read, have a pen or pencil reading with some scrap paper to jot down notes of your own as if you were lecturing to yourself. Rewrite important facts and derive ( or rather rewrite ^^;; ) important equations. It may seem redundant but after you write things down in your own words, you tend to remember it better. Quickly finding problems to apply your newly found knowledge is also an added bonus. It's easier to learn something once you understand what the world this information is for, how it can be applied. Just some friendly college studying advice from another college junky ^^

1. Temperature is caused by random movement of the molecules and atoms. There is no noticeable drift velocity. Sound propagates in air by compressing it logitudinally in a periodic fashion. There is a macroscopic displacement every time a wave goes through a particular region. And well due to frictional forces, you will somewhat heat up the air if you played that hard but wave propagation through matter and matter's own kinetic energy are two different things. 2. Wind is "cold" because of convection. It helps take away the heat. So by blowing air on to something you are helping it cool down giving the "illusion" that the moving air is cold. Of course, if there is water on the surface that the wind is being blown on, you get additional heat escaping through the water evaporating. That's why it feels even "colder" when you stand in front of a fan wet. 3. Continued from what I mentioned earlier. With humans, the water evaporation effect is even more emphasized because we sweat. The wind helps take away newly evaporated sweat so that conditions are favorable for even more sweat to evaporate. In order to evaporate, the sweat (water) needs energy. This energy is from your skin's warmth. Thus you cool down and feel cool. 4. I'm not sure at all what you mean by this one. I don't know of any place on Earth where air is being sucked "out into space". o_o

You can always just pick up a calculus book and start learning on your own (that's what you'll be doing most of the time in college anyway when stuff gets exceedingly hard). I'm sure you could get a loan from your high-school bookroom. Else, most of us hang out at #SFN @ irc.blackcobalt.net

I believe that the nature of things is to be round. Planets are supposedly formed as left-overs of the sun. Hydrogen and other heavier gases coming together. Gravitational forces will ensure that they it will become round. The main question therefore is, what makes asteroids bumpy. As far as I know, asteroids are probably former planets, parts of planets, planetary debris that has broken off. They were not formed like planets, but I'm no asteroid formation expert. I believe there is still disagreement as to the origins of our very own asteroid belt.

My first time seeing a tokamak. Judging from the model shown at http://www-fusion-magnetique.cea.fr/gb/fusion/physique/trajectoire.htm From how I see it, the helical behavior can be accounted for by the Lorentz force. If the charge particle is in anyway perturbed from the magnetic field line, it will start experiencing a force: qv x B which will send it going in circles, but as it still has its angular momentum it will also keep going in the larger circle. The radial and poloidal diamagnetic drifts are phenomena I cannot see to derive from the equations I know. It is the equal to: Veb = (E x B)/B^2. It looks like an interaction that might happen within a magnet. I'd like to know myself how this electric-magnetic field interaction works >_>

Quoted from FOX. I just feel sorry for the poor squid. Imagine having your arm ripped off. I hear it won't be growing back either. All for the glory of human knowledge. Where are the animal rights =(

I think outsourcing is just part of the bigger picture, globalization. With the introductin of globalization, you get products from all over the world, retailers from all over the world making their land locally trampling over local merchants who cannot compete with the economies of scale. In the end there is an "improvement" in the quality of products and services in third world countries. A reciprical phenomenon is happening in more developed countries however. As third world nations, especially China become better educated, EVERYTHING is going to become outsourced. At first it was manufacturing, then it was R&D, and now even design. Remember how Apple engraved on each iPod, "Designed by Apple in California"? Apple probably believes that it's a selling point to show it is one of the few companies who are not simplying buying out designs from Taiwan technologist companies like many of its competitors are. So what happens when China can do everything the US can for cheaper labor? Those in the US are going to have to work for less or get screwed. In a sense, China is evening its standard of living with the US. If the China guy can live on $200 a month, why do you need to live on $4000. I take this as an effect of globalization.

Well here's my input on it. Ionization energy: the energy it takes to remove an electron from an atom (and its influence) so it becomes a free electron. Generally we speak of only the valence electrons (in the outer most shell). The energy needed to remove inner electrons usually goes into the field of particle physics rather than chemistry or materials engineering. Electron Affinity: As mentioned, it is generally the same thing. But noticeably from the literature I have read, affinity is used with materials that have a conduction band. Then the electron affinity would be the potential difference between the conduction band and free space. Commonly seen in semiconductors. The term for it for metals is the metal work function. Electronegativity: How good an element is at attracting electrons. This can help you look into the polar nature of some molecules, and which element will attract electrons more strongly. In any bond, the electrons tend to spend more time towards one of the atoms. It's not perfectly equal and electronegativity quantifies this.

no comment....

Well true, but in then again, there will be 100 job openings for java programmers for every 1 opening for RPG. Go careful over the math. I haven't heard about this one. Most things "computery" stay alive when there is a community or group supporting it, else it goes stale. Java and MS C++ is strongly backed and periodically updated.