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studiot last won the day on September 16

studiot had the most liked content!

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  • Location
    Somerset, England
  • Favorite Area of Science
    applications of physical sciences
  • Occupation
    Retired Technical Consultant

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  1. This is not actually true and demonstrates the difficulty with analogies. The radius of curvature at any point is defined as the radius of a circle which exactly matches the curve at the point concerned. The curvature is defined as the reciprocal of the radius of curvature. For flat geometry or straight lines the curvature is zero. If the curve is a circle then the radius of curvature is the same at every point. If we now let that circle expand so that the radius tends to infinity, the reciprocal of that radius tends to zero ie straight or flat. But for your parabola, the radius of curvature is different at every point and remains finite at all points between the vertex and infinity. So its curvature is never zero, except at infinity and the vertex. These two examples do nicely show the difference between local and global however. For a circle, changing the radius affects every point on the circle equally. That is global. For a parabola the fact that the parabola radius of curvature approaches infinity as the parabola approaches infinity does not affect (the curvature of) any of the points on the parabola which already have a finite curvature. Curvature for a parabola is local to each and every point on it. It's not zooming out that makes things approximately flat, it's zooming in.
  2. Only two 3 countries We already went through this in excruciating detail in a previous thread.
  3. Every system has its stengths and weaknesses so thank you to beecee for giving us the opportunity to fully discuss the one based on hydrogen. +1 A further thought / question occurs to me. What would be the design life of such a system? How would that affect the financial and energy whole life costs ? I note for comparison that since the widespread uptake of lithium based rechargeable batteries many are now finding the true cost when the batteries need replacing.
  4. Cornwall? Please note the correct current name of our country as shown on a passport
  5. Surely this is a simple application of The First Law ? When you have your vessel of hydrogen, liquid or gaseous, you have a change of internal energy ΔE = ΔH + PΔV The PΔV term will be at the high pressure within the vessel. All of that internal energy will be lost when the hydrogen depressurises to react at normal pressures.
  6. I look forward to your scientific amplification of this claim.
  7. Grown-ups read all the words Actually no I didn't introduce liquid hydrogen into the thread, the OP did. Quite rightly in my opinion, since discussion of the circumstances when liquid hydrogen may or may not be appropriate and the difficulties involved are very properly part of the discussion here. They are not irrelevant. And yes I did read all the words, which is why I replied offering you a link to a website discussing the some of merits of liqification. And yes you are avoiding discussing the gas which is already in use in liquified form for transportation purposes, notably LPG. @beecee Yes it is great to learn of improved methods of decomposition of water to generate hydrogen. But a good question is How much energy in the form of work needs to be input to collect and store hydrogen gas or liquid in reasonable sized containers ? Will not this reduce the overall efficiency if the system ?
  8. Sure. There's lots to learn about heat pumps and variations on the theme as well as thing's your mother (or the salesman) didn't tell you.
  9. New findings at Whitesands https://ww Earliest definitive evidence of people in Americas By Paul Rincon Science editor, BBC News website Published 2 hours ago image source, Bournemouth University image captionThe footprints belonged to teenagers and children who lived between 23,000 and 21,000 years ago Humans reached the Americas at least 7,000 years earlier than previously thought, according to new findings. w.bbc.co.uk/news/science-environment-58638854
  10. I can't see where you think I disagree with this. Indeed we had a thread on hydrogen fuel cell technology for heavy plant (the heaviest possible vehicles under the Construction and Use (C&U) regulations, about a year ago. I only just reposted the link in beecees hydrogen thread. Again I don't see where you are coming from. Your descriptions and figures for heat pumps are way off. We have had several in depth discussions about heat pumps here. I freely posted costing and perfomance data for the system I fitted in 2016 in one of those threads. But really you should start a thread of your own about heat pumps since they are nothing to do with hydrogen, and this is meant to be a politcal discussion about hydrogen. Great technical question again. +1
  11. Just to add that soot is made of carbon. Naphthalene produces sooty deposits and is a widely used industrial feedstock. The minerals listed are refractory oxides, and therefore more likelyof artificial rather than geological origin. dunno about an actual explosion, stacks and chimneys are(used to be ?) cleaned by burning off sooty deposits. hence the night time display of sparks I referred to. The updraft from a powerful stack can carry particles quite some distance.
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