mezarashi

Sorry for the slow follow-up. How induction motors work is not an easy mechanism to explain. Usually induction motors are introduced at the very end of an Electric Power and Magnetism course in college that covers 3-phase power, although I feel it is still possible to understand nonetheless. It'll be some interesting reading indeed as these motors are the ones used in almost all industrial/commercial applications. Some of your house hold fans as well. I think the best possible link I've found on this is probably: http://www.windpower.org/en/tour/wtrb/async.htm A couple of other things you may need to know to read this. It is easier to start with how an induction motor works. An induction generator is simply an induction motor that has its rotor turning slightly faster than the "synchronous speed" rather than slightly slower as in an induction motor. One second a motor can turn into a generator. Wind Mills which use induction generators, need to switch their induction generators on and off depending on the turbine speed, because once the rotor fails to turn at a certain speed, it becomes a motor and consumes energy from the power grid. On the other hand, you see here that an induction generator needs a constant "excitation source". They don't work off the bat. A properly configured DC motor running off gas should usually be able to jump start one. Induction motors generally run on 3-phase power (3-wires). Your household plug is 1-phase (2 wires). 3-phase means that the sinusodial wave-form of the 3 lines are 120 degrees off from one another. 3-phase power can be created locally through use of capacitors and inductors which create an increased lead or lag in the current. There are two main components to an induction motor, the stator and the rotor. The stator is where all the electrical connections are made. The stator is completely stationary and does not move at all. The use of three phase power enables the stator windings to imitate a turning magnetic field. These magnetic field lines cut through the rotor as they rotate. Notice how the rotor is connected to nothing. The squirrel-cage rotor is not connected electrically. The existence of the cage bars is enough for the induction to occur and the rotor to start moving. This rotor is of course connected to a mechanical shaft of sorts where the energy is being delivered or transmitted. There are other noteworthy but slightly more challenging topics on the induction motor, like operating speed, load considerations, properly starting up an induction motor (I remember a friend blowing up a few in my electric power labs), torque produced by induction motors (varies with speed), power factor, and voltage regulation.

I think "commutator" is generally used when you are generating DC-current from a turbine (dynamo). Although I understand that it would probably work. In practical AC generators, electrical engineers use either synchronous or induction generators. In your case of a wire rotating between two electromagnets, this would be most similar to an induction generator. Induction motors/generators however dont use simply a wire. They use a squirrel-cage rotor. Its like two rings connected by some 12 long bars. Each pair of opposite bars acts like 1 loop. The cool thing about this is that it doesn't require any brushes at all !

Personally I think that the whole question of what was there at the beginning of the universe is absurd. It's like the good old question what came first, the chicken or the egg, because you can keep asking questions. If the big bang was the beginning, you could ask, then what was before the big bang. What caused the big bang? How was the "universe" like before the big bang. If the big bang isn't, and it's part of a perpetual cycle of expansion and collapse, then the questions are, what started this cycle? When did this cycle begin? Will it ever end? What was there before this cycle started? Why did it start? But back to the topic, there is a theory that predicts this endless expansion crush, string theory. String theory says that all the laws of the universe would remain the same if everything was inversed their planck length. Meaning that after the universe collapses to a size equal to the planck size, it would in fact "expand", because you can't tell. I'd personally like to believe in these perpetual cycle theories as well, although we don't know how true it all is

Any "jerks" you feel while driving is caused by acceleration. There is a difference in velocity (speed) between the car and your body. Acceleration is defined as a change in velocity. You "feel" acceleration when a force is exerted as a result onto your body. (In fact acceleration is caused by force) To understand this fully well, just understand that all objects tend to continue in their state of motion unless acted on by a force. Meaning that when you press the acceletor, your car speeds up, but your body wants to continue at the slow speed. You feel the pressure of the of the seat behind you pushin on your back so you go faster and finally attain the same speed as the car. If you suddenly hit the breaks or do anything to change the car's velocity, you'll soon feel "jerks" because your body doesn't want to change its velocity.

The mA is most likely a unit of time, and my first guess would be in the millions of years rather than milliseconds. This *is* star formation. It took look a billion years or something for Earth to form after the Sun cooled down. So if it makes any sense, I would guess it to be 0.5 million years. Your question on gravity. Yes, everything with mass in the universe is involved with gravity, meaning they are pulled in by other things, and they in turn pull other things towards them. The magnitude of which they pull depends on their mass. The bigger you are the harder you fall they say. The question of 'what is gravity' is more profound I think. There probably isn't a final theory on all of this yet, but the best model for it as far as I know is Einstein's general relativity. Gravity is caused by the bending of the space-time continuum (the fabric) itself. The more simple explanation usually taught in highschool is that gravity is one of the four fundamental forces of the universe: gravity, weak, strong, electromagnetic. Gravity is like a property of mass, so all mass contributes to the gravitational field. Goodluck in your studies ^^

Wow, your last post there sounds like some great philosophical statement. /me ponders

This depends on what level the electron was on. The lowest level it can be in is n=1, so if it has enough energy to jump 1 level, then obviously the answer is (a) n = 2. 1+1 = 2. My own calculations show that the photon gave 10.216 eV of energy to the electron, thus allowing it to jump from n=1 to n=2. n=1 (-13.6eV), n= 2 (-3.4eV) a difference of 10.2 eV. Note that at 0eV, the electron is free from the nucleus (conduction band).

Hi there, sorry, I didn't follow up on this post. Let me draw a picture for you to illustrate. Update: Don't ask me why the vector math is this way. Ask the mathematicians. They've given us engineers the tools that are consistent for the calculations needed.

Well, this is a acid-base reaction, that will neutralize the two into water and a salt: HCl(aq) + KOH(aq) -> KCl (aq) + H20 (liquid) correct me if I'm wrong on the solubility You will need 1 mole of HCl for every mole of KOH you have. I'm sure you're familiar with the mole unit if you're currently doing chemistry. You will need to make use of the periodic table and calculate the molar weight for the compound: HCl and KOH HCl = 1H + 1 Cl = (1.01g/mol) + (35.45g/mol) = 36.46g/mol KOH = 1K + 1O + 1H = (39.09g/mol) + (16g/mol) + (1.01g/mol) = 56.1g/mol So the ratio of HCl and KOH would be 36.46/56.1 For every 36.46 grams of HCl you put into the reaction, you will need 56.1 grams of KOH to use it up.

I believe that the US along with many other countries do. They will face their own consequences of course. According to economic theory, you can never get anything for free. The first and foremost effect is probably that of inflation. If you have too much of your money going around, it becomes worthless. Although as long as the US can continue to keep its GDP high, there will always be things to buy from the US, the money is still worth value. That's why the US is the only country in the world that does not need gold reserves. Everybody believes in US technology and US markets.

Asexual reproduction simply means that the reproduction does not require the concept of male/female. Like in humans, we need the male sperm and the female ovary to unite and fertilize, so in effect, if there was only 1 female on the planet, there would be noway we could reproduce. However, for asexual species, like some fish as well, they are both male and female!! now take that , makes the bisexualism in humans seem normal. So they can produce the necessary cells that will self-fertilize and become life. Cool right?

If you want two people to play the same game on the same computer, then online sites are probably not your thing. Online sites were designed for networked game play, and with today's state of technology, having 2 computers per household isn't too much to ask, so games that can be played 2 on 1 PC are getting more and more rare. If you want to try your luck however, you should look for those older games that you can download and run without any internet. You'll probably find better luck there XD

This sounds more like a driver problem to me. It's not that there aren't any options to increase the number of copies, but rather your printer is not responding to the request. As Windows98 and Windows2000 use completely different kernels, you will probably need that. If that isn't the problem, then I really have no idea. Computers are just like that. >.<

What he means is just that any device engineered by us has a range of operation. Beyond this range, you cannot expect any precise or accurate results. What was the scale on your scale? The cause of the inproportionality may be due to many things depending on the design of the scale, so I wouldn't know.

To the original question: If you divide the linear velocity (m/s) by the orbital radius (m), then you will get the angular velocity in radians per second. Frequency would refer to revolutions per second. Doing a simple calculation using for example a 10m/s linear velocity and a 10m radius will verify that this is correct. To SpaceTime: Well first off I'll need to assume an approximate circular orbit. I don't have experience with calculations involving elliptical myself. In anycase, the correct approach I think would be an addition of the resultant vectors. This concept is more clear with the use of vectors. The angular velocity vector actually points in the direction perpendicular to both the radius vector and the instantaneous linear velocity vector. The velocity relationship: v(linear) = OMEGA(angular) x r(radius) as found in AP Physics or more advanced dynamics courses. In effect, if the Earth is circling the sun in a counter clockwise fashion, then this vector points up (by the right hand rule). Now you can also similarly consider the angular velocity of the Earth on its axis, and add the parallel vector components. The Earth is tilted by 23 degrees or so I believe. The answer is in radians per second (the standard unit for angular calculations). Edit: All the radians -> radians/sec

For the people inexperienced with Japanese culture, yes, these "cartoons" make up a great deal of Japanese entertainment. In fact they are not considered cartoons at all. People of all ages watch it. Some of their "cartoon" shows (anime) air at midnight or 2 AM (obviously not for kids). Similarly in their adult video industry, there is a large market for porn cartoons, known as "hentai". A search on google for "hentai" or "lolicon" will land you some relevant results. They can be used as substitutes for sexual stimulation, and to many people are actually better, and do not need to break the law. Not all hentai is themed on child sex of course, and different people enjoy different themes. It is somewhat disturbing to know however, that alot of people enjoy depictions of what appear to be underaged girls.

Interesting question. Reminds me of my geometry days. Let me have a go at it using the classical ways >_> Updated: Hopefully that will be a bit helpful. It took me sometime after all. This problem was more confusing than I thought. Anyway, the whole problem here is trying to the find the area of that small unshaded white area in the square box. The picture i made above represents it as yellow. Well obviously if we can find the area for this two circle case, we can apply it to the four circle case easily. So let's start from here. To find the area YELLOW, it will be most convenient by first finding area BLUE. I couldnt find a way to explain this properly so I drew another picture So basically the strategy here as you can see, is to find the dark green region which is basically the BLUE area in the first picture. You will subtract the triangle formed by the red lines from the green circle segment. Now to find the dimensions. We know that since it's symmetrical, the x length of the triangle is 5. The y can be found using the circle equation: y^2 + x^2 = R^2 (in this case, R = 10cm) This will give you y = 8.66cm Now we know that the height total of the triangle = 2y = 17.32cm Using the 1/2 x base x height formula, the area = 43.3cm^2 Now use the tan rule to find the angle. arctan ( 8.66 / 5 ) = 60 degrees, or 120 degrees (out of 360), meaning this is 1/3 the circle's total area. Using the fraction 1/3 x pi x r^2, we get this area to be: 104.72cm^2 Subtracting the two from each other: 104.72-43.3=61.42cm^2 = Area BLUE So now that we know area BLUE, we return to the first picture and see that BLUE + RED = 1/4 circle area, we substitute the values in to get: Area RED = 1/4 x pi x r^2 - Area BLUE Area RED = 17.12 cm^2 Lastly, we know that BLUE + RED + GREEN + YELLOW = 100cm^2 (also RED = GREEN) Area YELLOW = 100 - BLUE - 2*RED Area YELLOW = 4.393 cm^2 Hurray! So we now know that tiny area that is not included in the red shaded part of your diagram. All we do now is take the area of the square and minus away 4 of these: Shaded region = 100 cm^2 - 4*(Area YELLOW) Shaded region = 100 - 4*(4.393) = 82.4 cm^2 Pheew. I hope that's correct. I haven't checked, but it makes logical sense to me. /me sleeps

I guess the only person who would know is the guy who actual wrote that, but you can conclude a few things. First of all, this is probably referring to your harddisk as the rest of the computer comprises mainly of solid state devices in which gravity simply has negligible effect. First of all, G means gravitational acceleration (precisely 9.8m/second/second on the Earth's surface). Have you ever watched one of those documentaries on military aircraft, saying how they have high maneuverability and can pull 10 G's. That means that they are accelerating 10 times the speed of the gravity. If you were to sit on something that is accelerating upwards at 10G, you would feel 10 times as heavy. And that's VERY heavy. Most people would probably lose conscienceness at less than 10G due to blood not circulating properly. With regards to the computer. You probably now from physics that when something changes velocity, it must undergo acceleration. For example, you drop your laptop off from a 2 story building. It will accelerate at 9.8m/s/s (1 G) to the floor, where it will probably come to zero velocity in a matter of milliseconds. You can calculate this acceleration by doing (change in velocity/ time). Now if this acceleration exceeds that specified (23G = 23*9.8), then you're going to have a problem. In real life, yeah, that would pose a great difficulty because nobody has a millisecond stop watch to time the time of impact during a fall. But then again, neither do the engineers who designed it. Depending on the elasticity of the laptop and the angle of collision, it may or may not survive the drop (although a 2 story drop is obviously going to obliterate it ) The vibration component probably refers to oscillatory motion. For example your on a rattling train. The moving features of your harddisk may not be able to accurately function if there is too much rattling. The shock component refers to sudden impact such as a fall. An impact over 23 G would probably cause it permanent internal damage. The faired square wave probably indicates this impulse, although I'm not sure what is meant by the velocity change of 508cm/sec. The engineers of the harddisk can't say for sure that even a 2cm fall won't do damage. Thus the use of Gs. For example, if it happens to land in an awkward angle, it may end up pulling over 23Gs. (consider changing the velocity from 2cm per second to 0cm per second in 0.01 milliseconds = that's 204G's!) So in effect, intuitive judgment is the best means. Take good care of it ^^

That's quite an ambition to say the least. The unification refers to the unification of the four known forces: gravity, electromagnetic, weak, and strong. Some 'general audience' books that you can read to give you a start on the subject of relativity, quantum physics (the attempted unification of quantum physics and relativity), and other crazy ideas would be: A Brief History of Time Stephen Hawking Hyperspace Michio Kaku The Elegant Universe Brian Greene I remember seeing a couple of these books in my highschool library back 3 years ago, so I think that won't be a problem. Happy reading

I'm not sure if that will be as easy as it seems. In actual fact, the "constants" mew not and epsilon not are not constants, but parameters that describe a certain medium. In this case the parameters in free space. In lossy mediums, you will even get complex permittivity and permeability. Permittivity and Permeability describe a kind of characteristic of how electric and magnetic fields are able to fluctuate, and knowing that light is the fluctuation of electromagnetic waves, and propagates in the perpendicular direction of these two fluctuating waves, you can see that there is a relationship. If you could tell me more about your theory, maybe it'll get interesting.

Maybe some were born with it, but for the record, pedophilic tendencies can be acquired. A good example is anime. Anime naturally breeds pedophilia, and many I know (*eyes himself*) have started to fall victim.

Okay this is based on Dapthar's original post. I orignally had a slightly different method in mind, but I also started out using the multiplication by the conjugate. [math]\lim_{x\to\infty}{x+\sqrt{x^2-4x+1}[/math]. [math]x+\sqrt{x^2-4x+1} = (x+\sqrt{x^2-4x+1}) \cdot \frac{x - \sqrt{x^2-4x+1}}{x - \sqrt{x^2-4x+1}}(1)[/math] [math] = \frac{x^2 - (x^2-4x+1)}{x - \sqrt{x^2-4x+1}} = \frac{4x-1}{x - \sqrt{x^2-4x+1}} = \frac{4x-1}{x - \sqrt{x^2-4x+1}}[/math][math]\cdot \frac{\frac{1}{x}}{\frac{1}{x}}[/math] [math]=\frac{4+1/x}{1+\frac{1}{x} \sqrt{x^2+4x+1}}[/math] let t = -1/x, such that [math] \lim_{x\to-\infty} = \lim_{t\to0} [/math] [math]=\frac{4+t}{1+t \sqrt{\frac{1}{t^2}+\frac{4}{t}+1}}[/math] [math]=\frac{4+t}{1+\sqrt{1+4t+t^2}}[/math] By substituting t = 0, we get our desired 2.

I side with the people who don't buy it. First of all I think the survival of the fittest mechanism will be the invisible guiding hand to ensure that we don't dumb ourselves into extinction. Secondly and most importantly as an engineer I realize, our civilization isn't built upon intelligence, it is built upon knowledge bases. Why do we go to school and university to learn all the things that we do. Do you think all the engineers that build the things you use everyday are the smartest people on the planet? Of course not. They were trained to do so. The wisdom of their trade was imbued forcefully upon them. A scientists at NASA does not know, and I would not believe even if he said so, to know every single detail fo the space shuttle. Nor did he discover the shuttle when he became first employed. He is building the shuttle upon known knowledge. He knows what works, and what doesn't because of the past. He has just happened to be trained into being able to understand those manuals and methods. As long as we have this knowledge base of technology and methods, we will continue to be able to move forward.