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swansont

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Everything posted by swansont

  1. If you're doing an identical task, then the task itself doesn't matter. That will come into play if there are different efficiencies in doing the task, but you can still treat that as a general condition. You're just looking for cost per some unit of energy. http://www.npga.org/i4a/pages/index.cfm?pageid=914 gives some numbers in terms of millions of BTUs (because it's US and we're idiots, not using metric) and according to that, natural gas is less than half the cost of electricity here.
  2. I was not considering evaporation at all, just the issue you presented, which was surface area.
  3. Your picture is showing the top view of a 2-D representation of the waves, where the lines are the peaks. Amplitude of sound is related to the pressure or density of the air (or other medium)
  4. Paper journals still exist, and it costs money to publish.
  5. Slow. If it's analog, the signal is red-shifted, i.e. a lower frequency. If it's digital, the clock rate of the sender is slow, so your data transmission rate is slow as measured by the recipient.
  6. I thought Kepler's third law was that the square of the orbital period is proportional to the cube of the semimajor axis. Your source mentions an equation (6.11) that is not in your attachment. How about including the derivation of that, so we can see exactly what the author is talking about and how r'A and rM are being used. (it also gives 66190 km = 41100 miles)
  7. That breakup probably comes at the expense of the water's kinetic energy, and you'll recover it when the water coalesces at the bottom.
  8. The doctor's mistake was telling the patient why he/she wouldn't treat her. Lie, and say you aren't taking on new patients, or something similar. But California has anti-discrimination laws that cover this situation. If you don't like it, vote with your feet, or stop performing the service altogether. I think it's a different argument. A doctor specializes and doesn't do certain procedures. Do we make an orthopedist who specializes in shoulder injuries treat your broken toe? If you don't do abortions, you don't do abortions. It would be the same argument if the doctor only performed abortions on lesbians. No, I don't think you are.
  9. Sound doesn't really carry off much energy. 90 dB — which is pretty loud — represents a milliWatt. There's a trivia bit about how yelling for ~8.5 years has the same energy as it takes to heat a cup of coffee. So let's do a quick calculation: The splash of a liter of water over the course of a second, from a height of 1 meter, is almost 10 watts. This is probably less than 60 dB (a microWatt) if you're a meter away. Assume a point source. The sphere is 10^5 cm^2, so what fraction of that area do you detect with your ear? 1 cm^2? 10 cm^2 That means that the sound is less than 1% of the energy, and probably much less. The Horseshoe falls are about 50 m tall. That's a tenth of a degree or so, assuming all potential energy is converted into thermal energy.
  10. Heat capacity of water is a calorie per degree K cc, and a gram of water is going to gain 9.8e-3 J of kinetic energy per meter. Since it's 4.18 J (1 calorie) to raise the temperature 1 K, that's a paltry 2.3 milliKelvin per meter If you could build it properly, just drop a bomb calorimeter. Falling water is falling water — it doesn't have to be a "waterfall" You'll want the mass of the water to be the dominant mass term, and a low-mass material that doesn't deform, so that the water's energy is what you're actually measuring.
  11. What if the overall demand increases faster than the "self generated" sector? Imagine replacing most gasoline with electricity. In the US, that's about a billion kWh per day of electricity required, which is comparable to residential electricity usage. IOW, demand doubled, and this without more gadgets and a larger population. I'm not worried about corporations' ability to turn a profit.
  12. They're allowed to. It's the government that can't deprive you of this (in the US, at least).
  13. It also potentially becomes an attempt to present the quote as an absolute truth, absent any context that might limit its applicability. Phenomena may not be real until they are observed, but theory can tell you where to look. That saves a lot of fumbling around.
  14. The aether was the medium and preferred reference frame through which light purportedly traveled. Since stellar aberration had already been observed by Bradley in 1727, scientists knew we could not be stationary with respect to the ether. This is why M-M did not expect zero as a result. AFAIK the aberration indicated that the sun should be the reference point under aether theory, since it was an equal amount no matter what the position of the earth was, with only a direction change. (though there were other complications, but then, the model was wrong)
  15. Not really sure what you mean by this, or what definition of "random" you are using. The observer "collapses" the wave function, so the electron or photon is not in a superposition, which means you don't have states that can can interfere. This destroys the interference pattern.
  16. Yes, a net neutral plasma will behave much like chatges in a conductor. I thought this effect has been observed in charged beams as well; that's the scenario I couldn't understand.
  17. swansont

    Magnets

    The present situation is a magnet that has lost much of its magnetization. I would think the local heating during machining would affect the magnet, which is another reason to machine it first.
  18. swansont

    Magnets

    If you're heating the material you don't have to do as much work to "unstick" some domains, since the thermal energy has done that for you.
  19. And could anything be less reliable than that which does not exist? Whoa. Zen rush.
  20. When I edited a post, it gave me a "vote now" option instead of "save"
  21. Time and History of Rocketry & Space Travel aren't scientific sources, either. D H gave an equation. Stating Newton's gravitation law and doing a little math doesn't require a citation, so complaining about the lack of one is a rather hollow complaint. If you think the stated work is wrong, then rebut it. And scientists typically work in SI units. Not really scientific sources here, either. A fallacy of distraction. D H has been providing the former, and not the latter. Focus on the subject matter.
  22. I'm blocked at work now, and the https doesn't work. No surfing while monitoring other things, and no surfing at lunch or on break. Proxy servers are strictly verboten.
  23. I don't get that impression from the article. They say there would be fewer hurricanes than we currently have (or have had in the past) and that they were surprised by this. The only discussion of other models says that they agree. "The same prediction has recently been made by other studies using global climate models, and the similarity of the two predictions enhances confidence in the results." So the claim that there were predictions of more hurricanes, and the implication that that this is a contradictory study, would appear to be incorrect.
  24. But the article starts with "If two particles are “entangled”, so quantum mechanics says, any tinkering with one can cause an instantaneous change in the other, no matter how separated they are." Ugh. No "change" occurs. Once you've made the measurement, the particle is in a particular state. Tinkering with it won't do anything to the other particle, since the entanglement will have been lost.
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