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Everything posted by Externet

  1. Hi. A toy car receives the impact of a horizontally going projectile onto its solid, metallic, vertical rear bumper, and the projectile bounces back. The same toy, weighing the same as before with a springy or rubber bumper, receives the same projectile and it does not bounce backwards at all, just drops vertically after impact. Which case will push the car more distance because of the impact ? Miguel
  2. Hi. Post ALL the rules for the task up front. Miguel
  3. Hi. http://www.blacklightpower.com/ Miguel
  4. Two light sources S simoultaneously turned on; what is the relative speed (collision speed) of both light beams when propagation wavefronts meet midway ? S---------><----------S c-(-c)=? Miguel
  5. Hmmmm. But I will learn nothing downloading. And Spybot caused much trouble a year ago when I used it in my compfuser at work; will never get back there. I use AdAware ; McAfee Corporate and Yahoo popup blocker. But that is not the point. Am after the batch file. I will study how to make such batch, and try to set it to happen every monday. Miguel
  6. Hi all. OK, Bettina. Your response makes somewhat more sense to my dumbness. I do have anti-spy and anti-virus and all that which is not the subject here. And I will not get another firefox or whatever that will take me a year to learn. ...maybe And for all you, a batch file it may be a piece of cake, for me is hebrew, I do not know even what is a command line . So I open Wordpad as if I was to compose a letter; Write the steps I would do when deleting those files manually, in the same sequence, with proper syntax, save it into something you call 'startup' that I have no clue where it is... And this text named batch file would be something like: Open Windows explorer Go to Windows directory and open it, Select cookies folder and open it; select all files; delete; click yes if asked I want to send to the recycle can; when done, open temp internet folders; select all; delete all files; click yes if asked I want to send them to the recycle can; when done, empty recycle can; Display "Cleanup done, continue" for 2 seconds End of program At least you will get a laugh out of the above; but I told you, never done, and not much clues on how to . If an example can be posted here (as it is a piece of cake for you); I could taste some of the cake. Thanks for holding my hand, Miguel
  7. Hi. How to execute a set of commands automatically after finishes initialization (Win98 ; Win XP)? Getting into Windows explorer, I manually delete 'temporary internet files' and all 'cookies' from within their folders periodically, which is supposed to happen when the option to do it when closing the browser is selected under Internet 'tools' But it does not happen as expected, and besides cookies being kept in the cookies folder, they also hide in several 'internet temporary folders' along with more crap pumped by peddlers and spies of all sorts. To the colorguard of computers idiots (me), is not easy to implement such 'Startup?' set of actions. Can someone tell how to do it in simple terms and clear steps ? Miguel
  8. Hi. You may be under the wrong impression seeing one single cable that actually has many wire pairs in it, each pair handling only one communication path. If it is truly a single metal pair, can be digital communication, where the voices of multiple simoultaneous users are sliced in tiny portions, fed into the single wire pair (multiplexed) and at the other end, the slices sorted and put back together and properly re-routed (demultiplexing) Links between telephone central stations use the same multiplexing method on a single fiber optic, with thousands of rapidly sliced signals. Miguel
  9. Hi. Scuba tanks are rated ~3000 psi, ~80cuft.. If you fill one at full capacity, you have a good chance to rip your head off playing with its valve and pressure. Do not even dream of a garden hose! That is not a toy and can be lethal in wrong hands. Miguel Scuba diver
  10. Yes, Alienufo. As if you discover a reaction to reverse vulcanization to turn old tires back to rubber to make new tires. Selling that formula/method could yield figure$ you cannot imagine. Miguel
  11. What common materials/elements could be the ones used in this gadget? : http://dragonet.com/fhp/ Has 8 cells to yield 12V, and only anodes are consumed in operation.
  12. Hi . Does galvanic protection under seawater by the use of dissimilar potential metals create an electric field and electric current in the water? If yes, to what extent ? A mile apart chunks of zinc and iron, will there be an electric current between them ? Miguel
  13. Yes, for the same motion the stronger magnet will induce more current; but takes more force to push the strong magnet to achieve the same motion. Are you reading?
  14. Thanks gentlemen; that was very clear, simply better than some text books. The rectenna would be what am after, but in semiconductor style construction, perhaps using materials with the property that weak photons can knock their electrons off. Miguel:-)
  15. Hi. ..."Your kinetic energy is being changed by the magnetic field into electric is what you meant? energy. "... I would say that the stronger magnet takes more effort to pass it over the wire; then, the kinetic energy is different in every case. More force to move the stronger magnet, less for the other. The efficiency would be the ratio of the electrical energy generated and the kinetic energy requiered to move the magnet to produce such generation. In small experimenting driving magnets by hand, you cannot discern those minimal differences. You would need measuring instruments to show such. Just imagine a permanent magnet toy motor, -used as generator- how much torque needs to be spinned when electrically loaded. The same motor with no magnets in it (extreme case of weak magnets), will need much less torque to spin it with the same electrical load. Hope it helps, Miguel
  16. Thanks, gentlemen; am learning good from you. If all energy are photons, visible light range or radio range, the point of view can be changed from visible light spectrum to radio spectrum. As ..."IR has quite a low frequency and so it has low energy"... Focusing the center of attention to radiowaves (also photon EM energy) ; the IR spectrum has a MUCH higher frequency and higher energy than radio. Trying to express myself better: A plain microwave oven, rated say 1 Kw emits EM photons at 4 GHz. If its frequency is increased (towards IR) the energy emission would be greater (am not talking about its cooking abilities) as : "E = hf E is energy h is Planck's constant, simply put it's just a constant f is frequency" Then the new rephrasing would be... ¿How to manufacture a PN junction cell of some kind that will convert RF into an electric current and performing up to IR ? Is the explanation still the same -too low energy- ? If so, that 1Kw ! microwave oven is too little energy to recover any from its confined chamber by means of some sort of cell ? Thanks, Miguel
  17. Agreed, solar cells do not work with heat radiation. That is the point. Rephrasing... What would take to make a cell similar to solar but centered in the far IR ? -- "thermovoltaic" instead of photovoltaic -- It is not about sensors, as the ones used in infrared cameras and thermal imaging, those are fine for detection but not for generation. What does waaaay too low energy refers to ? The heat radiation to be collected or the electrovalence energyband something of the PN junction ? Miguel
  18. Thanks all for the explanations. I was interested in the radiation form of heat transmission only, it is difficult to understand how simple friction of two electrically inert bodies can radiate electromagnetic waves (heat).
  19. Oh, boy ! Thanks.- By Swansont : ...You shouldn't distinguish between the photons and the radiant heat. They are the same thing."... By Tycho? : ...Radiant heat is EM radiation, so its made up as photons just like light and x-rays. Both opinions on the same track... perhaps am influenced by the word 'photons' I thought being visible-only light emitting... which is not visible in far infrared (heat) radiation; but still named photons ? OK; next step. ¿What would it take to make a solar cell with shifted response towards the far infrared spectrum; if it is a photon emission, could dislodge electrons from a PN junction and create some electrical current when exposed to radiated heat ? Miguel
  20. OK, thanks. So it is an electromagnetic wave. As in distant atomic bomb explosions, photons from the flash are perceived simoultaneously with the heat; the shock wave and noise is obviously later.
  21. What is the propagation speed of radiant heat?
  22. How does heat radiate ? What is that emission of heat ? Is it some sort of rays, electromagnetic waves, particles, molecular vibration ? A body placed between a radiated heat source and its target can block or absorb it. What is actually traveling trough the air from the hot body to the being heated one ? Miguel
  23. Could SZn be used as paint, mixed in some clear base to be applied onto walls to provide some glow from its luminiscent properties ? Has it been done?
  24. Hello all... Two identical air compressors in series, both running at the same rpm. But the second in reversed flow, as to force expansion of the air compressed by the first one. ¿ Will there be pressure in the pipe joining them ? A-------C~~~~~?~~~~~E-------A A= atmosphere C= compressor ?= is there pressure in this joining pipe? E= expander (reversed compressor sort of a vacuum pump) ------ = pipe ~~~~ = radiator or finned pipe or cooling coil Anyone remembers ROVAC ? Miguel
  25. Heating a home in general is considered more expensive than cooling, if both energy sources are at the same rate. Cooling process is lossy because of the compressor, evaporator and condenser inefficiencies, but the temperature gradient overcomes those losses. Cooling happens when the temperature is about 32 Celsius, and you want to extract heat for a delta temperature of about 10 degrees to get a comfortable 22 Celsius. Heating happens when temperature is around 0 Celsius and you want to add heat to reach about comfortable 20 Celsius. The delta temperature is twice for typical heating, the cost is nearly twice for heating. If you want to heat / cool the same amount of degrees, cooling is more expensive. Miguel
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