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Everything posted by tvp45

  1. Yes, I throw my vote in with ewmon and davey2222. The effect can be readily seen by using a helium birthday balloon, which "rises" in the direction of acceleration in the same fashion as heated air. The layer of air adjacent the windows would of course be heated.
  2. These folks sell a nice variety of constant force springs, though these may be different from what you had in mind. Even if the springs aren't right, their collection of mechanical items is a real "candy store" for the tinkerer.
  3. Transformers are fairly large, expensive, and heavy. It really depends on your application.
  4. I think it's safe to say that no one would ever silence a motor which purports to violate conservation of momentum. There doesn't seem to be any way from the video to see the "trick", so consider it an interesting gag.
  5. I'd recommend Les Miserables by Victor Hugo. Paints an accurate picture of the struggle between moral right and legal right. Huck Finn by Mark Twain. Shows America in the best and worst lights through the eyes of a young man. Street without Joy by Bernard Fall. Shows the ultimate failure of colonialism in a vivid manner. The Guide for the Perplexed by Moses Maimonides. A practical philosophy book that remains topical after 800 years.
  6. You would have to know something about the impedance of the shockee (?) and the output impedance of the fence unit.
  7. Voltage is the potential energy per unit charge. There is always a potential difference causing current, even when it is very tiny. Let's say you have 3.000 V at point A. This means relative to point B. The end of the resistor nearest point A might have somethin like 2.9989 V, the small difference being what it takes to make the current in the wire. Likewise, at the end of the resistor nearest point B, you might have 0.0008 V, again the small potential difference being needed to have current in the wire. We normally just ignore the small potential differences across the wires.
  8. Louisiana has added a "defense of marriage" article to their constitution, implying they have the sole control over marriage within the state. Louisiana has a "due process" clause in their constitution. JP's are state officials under their constitution. Really a "no-brainer". The man has violated his office and needs to be removed forthwith.
  9. I quite agree. I've never been blessed with extraordinary intelligence or a great education. So, I've made it a point to notice who is smart and then I listen to what they say and try to remember as much as I can. I freely, and often, admit that I don't know something, and that gives me the freedom to go find out. Turns out I do have a good knack for figuring out who really does know things vs who just puts on airs.
  10. Hello, Not a strange question, but a loosely defined one. I sort of know the answer because I get to tie up the little sand bags that anchor the balloons at the annual fete at a local adoption agency. But, I think this is a class assignment? So, you must have held such a balloon at some time. Can you close your eyes and remember the pull on your hand? Would you say it was enough to lift a toothpick? How about a small coin? A pack of gum?
  11. An old idea. Follow this link to a song of the American Civil War. http://books.google.com/books?id=frwYDKDm6RcC&pg=PA51&lpg=PA51&dq=gunpowder+american+civil+war+song+urine&source=bl&ots=Fm5j1txB-a&sig=KUa_T2bIdIYNK3oLHUf5p9cm7Gg&hl=en&ei=T626Sr35BJOJtgf-kdX7CA&sa=X&oi=book_result&ct=result&resnum=10#v=onepage&q=&f=false
  12. As opposed to just using a gearhead? Or, alternatively, why not a controller?
  13. I should think a strict application of Ockham would just be "We can measure local elapsed time heuristically." After that, it gets complicated.
  14. In general, that's not possible. Almost nothing is ever invented in isolation except the nutty things like a special torch for removing nose hair. Science, particularly advanced science, is collaborative, and there is a sort of "time" for certain things to occur. Think of Tesla, for example. While he was busy developing three phase motors in East Pittsburgh, the Europeans needed the same type of devices. So, people like Ferrari invented things much like Tesla at about the same time. So, the "secret" almost always gets out. Now, of course, if there were patents, then corporations can control the use of those for at least seventeen years. But, patents are public documents. People know of their existence. If somebody like Warren Buffet knew that Exxon-Mobil was sitting on a patent for running cars on gas, he would do a hostile takeover, split the oil company from the patent and sell both separately, becoming perhaps the first gazillionaire. Privately held corporations could, of course, be immune to a takeover. But, is there any evidence that anything like this has ever occured? Read John Baez's list of clues to detect a nutty conspiracy theory.
  15. Don't take the "Twins Paradox" too literally. It only seems a paradox if you ignore parts of the situation.
  16. Last evening I attended a meeting that was held in a classroom of an Orthodox Jewish education center. I noted there were no powerpoint projectors, no internet, no tv, no electronics at all. There were a ton of books on algebra, calculus, statistics, history, chemistry, etc. There were a number of posters with (seemingly) student-written math questions on the wall. What do these parents know?
  17. I've seen these kinds of machines for decades and often wondered why people might think they would work. It's easy to see why somebody with no technical background might think there's magic in a magnet (Lookit, Ma, the Westie chases the Scottie!), but so many high school graduates believing in such a weird thing? Then, the other day, I picked up a university physics textbook and happened to see a picture of a bar magnet. And there were field lines popping out of the north pole and running to the south pole, and the text even described those lines "emerging" from the north pole and "ending" on the south pole. Well, "Doh!", no wonder folks believe in monopoles.
  18. Geez. I did a little research and then reread the OP more carefully. You're right - I was had! Oh, well...
  19. I'd look at applied mechanics or fluid dynamics.
  20. Sorry. I missed the brightness violation. I suspect I don't understand his proposal after all.
  21. I think I understand your proposal. If so, there is nothing in principal that prevents your doing this, though I think you must do a lot of engineering yet. I don't see this as a lot different from the old parabolic reflector demo, and that is not very efficient and requires, I think, some sort of external energy in order to facilitate the flow of heat in a practical device. Were you to overcome the practical issues, I can readily imagine a legal quagmire over radiant rights, i.e., do you have the right to take radiant energy from the outside of my auto at an accelerated rate?
  22. If you're just starting out, there is nothing better (although somewhat old now) than The Forrest Mims Engineer's Notebook. Then actually build some of the circuits. They're easy and instructional.
  23. Take a 12 inch plastic ruler. Have a helper hold it between you almost closed forefinger and thumb such that the 0 is level with the center of your thumb.. Put a sheet of cardboard so that you cann see his hand. When he drops it, grasp it as quickly as possible. Measure where the center of your thumb is now. Work out the free fall equation for the time.
  24. tvp45

    spherical magnet

    A very practical way to see this is to try experiments with electromagnets, which are much easier to control. For example, you can take a long rod of iron and put identical two coils in the middle, each facing an opposite direction. You will quickly see that you can get two reasonably identical poles on the ends that are much weaker than what you have with a single coil. As you control leakage, the end poles approach zero. If you use a high mu rod and curve it back into an almost closed "C", with the ends only a few mm apart, the pole strengths will be vanishingly small. You can do the same thing with the spherical case (if you have a spare Magdeburg Sphere lying about), putting small electromagnets on the inside, all oriented out. At first, you'll get a mixture of N and S poles (One more concentrated than the other). To the extent you can make very tiny identical electromagnets, you'll begin to get overlapping N and S and you can imagine the field going to zero in your mind at least.
  25. It's hard to make any blanket statement about accomodation. Consider Kent Cullers, by any account a good physicist, who had to have various sorts of accomodations to do the required labs. Or, Steven Hawking. The key, I think, is reasonableness, and the folks in University "special students" offices sometimes don't know how to assess that.
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