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1271 Glorious Leader

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About studiot

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  • Location
    Somerset, England
  • Favorite Area of Science
    applications of physical sciences
  • Occupation
    Semi Retired Technical Consultant
  1. BBC article about a series of articles published today in Science about finds in Kenya spanning a million years of human development and evolution, including links to historic climate and other conditions changes.
  2. Good documentaries on Earth science topics?

    Yes, the BBC has produced some excellent Earth Science programmes and also issued them on DVD. Also good The power of the planet series
  3. A perspectives of the heat pumps

    Why do the bean counters of this world always insist on killing the golden goose? Geothermal can be overdone or it can be wonderful. I understand that in certain parts of Sweden (where they did a lot of it) ground source heat pumps are now banned as they created ground permafrost. Some civil engineering techniques depend upon ground freezing, which use basically huge GS heat pumps.
  4. Good morning, datlemondoe and welcome to SF. The second order integrated rate law is only as you state if the concentration of A is equal to that of B, otherwise it is more complicated as follows. If [math]\left[ A \right] = \left[ B \right][/math] Then [math]rate = - \frac{{d{{\left[ A \right]}_t}}}{{dt}} = k\left[ A \right]\left[ B \right][/math] But since [math]\left[ A \right] = \left[ B \right][/math] we have [math]rate = - \frac{{d{{\left[ A \right]}_t}}}{{dt}} = k{\left[ A \right]_t}^2[/math] On integration [math]\frac{1}{{{{\left[ A \right]}_t}}} = {\frac{1}{{\left[ A \right]}}_0} + kt[/math] Which is the expression you have. However if [math]\left[ A \right] \ne \left[ B \right][/math] Then [math]rate = - \frac{{d{{\left[ A \right]}_t}}}{{dt}} = k\left[ A \right]\left[ B \right][/math] We cannot replace the and the integration is more difficult. The result is [math]kt = \frac{1}{{{{\left[ A \right]}_0} - {{\left[ B \right]}_0}}}\ln \frac{{{{\left[ A \right]}_t}{{\left[ B \right]}_0}}}{{{{\left[ A \right]}_0}{{\left[ A \right]}_t}}}[/math] But k remains the same constant. Does this help?
  5. Hole burning in concrete floor outside

    there is no need to look elsewhere, though of course you might find a better idea. We have an engineering section here and this is a building problem, not a chemistry one. But never mind, that won't stop us answering. But how about the building details I asked for? in particular is the floor anything like this? There will be a thin layer of fine concrete above this called a screed, to form the surface of the floor for finishings - carpet / vinolay or whatever.
  6. Hole burning in concrete floor outside

    Hello Simon, I think we need more details. I can't see the Ytube it says private video. Why have you asked this in inorganic chemistry? Concrete is more engineering surely? Anyway details of this floor and the concrete would be appropriate. You call it a floor and say it has a void beneath it so what is above it? What is it the floor of? There is a form of construction which uses inverted T beams spaced one lightweight concrete apart. The lightweight blocks are placed on the heads of the inverted T, spanning between the beams and form a highly insulating floor. Some types of lightweight aggregate and some cements are made from partly burned clinker and power station ash (Fly Ash). There might be a particularly poorly burned piece in one block which has somehow been reignited, if you have this type of floor construction.
  7. The nature of uncertainty

    Uncertainty manifests itself in many ways, the exact details varying with the circumstances. Rather than argue over uses of FT, here is a clear cut classical example of uncertainty which also clearly demonstrates the difference between errors and uncertainty. A concrete beam spans between two walls and carrier further structure above it. Strength and deflection calculations involve the self weight of the beam, the exact span distance, the further loads imposed by the structure and so on. None of these are certain and modern practice uses what is known as partial safety factors to accomodate these variations or uncertainties. However it is also possible to make errors either in the measurements or the calculations which assume perfection in that respect.
  8. The nature of uncertainty

    I didn't say it was, I said FT s are used in classical Physics. Your point I was indicating is that uncertainty is inherent in the maths, not the measurement. It is there whether a measurement is made or not. Please note I edited my previous post whilst you were posting yours.
  9. The nature of uncertainty

    Good morning, Shauno. thank you for your reply. Please read swansont's reply above. Fourier transforms, for instance, are used classically. I think it is important to note that there is a difference between errors and uncertainty. Uncertainty is inherent in the mathematics and cannot be avoided. Errors are more tractable by various operational and mathematical means. Number (of moles) is one of the fundamental quantities and is a good example of something that is inherently certain, but still prone to the possibility of error. The next bit is not off topic because it is linked to uncertainty. I don't see how this relates to the full text of the comment in my post and the mathematical procedure was referring to.
  10. Back to the OP First off TakenItSeriously (please get a shorter handle) I am going to say +1 for encouragement. Iam am impressed by the reasoning of your case, this is best chain of reasoning I have seen you present. But you should beware avoiding mathematics because the best of reasoning is useless if founded on shaky premises. It is possible to reach the wrong conclusion from them or it is possible for two (or heaven forbid more) errors to 'cancel out', thus reaching the right conclusion for the wrong reasons. Looking at your statements of symmetry, the difficulty is that the symmetry of the Physics relies on a common variable. That is the symmetry is in the the same variable (one variable) in both aspects. The common variable in this case is the relative velocity. You have taken time from one twin's frame and compared it with time from the other twin's frame. So you are comparing two different situations. The actual symmetry works like this: Twin A sees twin B receeding at 0.8c Twin B sees twin A receeding at 0.8c You have, however correctly identified that what happens to the rest of the universe is the basis of the logical resolution of the paradox. Note that the travelling twin (B) has no means of measuring the distance to his destination, once he has set off.
  11. New Toba study publishes suprising data

    Thanks for the cooperation. +1 I think science sites work best that way.
  12. The elevation difference would only have a significant effect if the higher level placed the panels clear of some (partial) shading object such as another building or trees etc.
  13. A BBC report about the the Toba volcanic eruption that sheds new light on the human response during the winter that must have followed and its effect on human evolution. This appears to run contra to previous ( conventional) thinking
  14. NMR Spectrum for Phenol

    What a wonderfully clear explanation, HI. thank you +1 Hashtag, I didn't know they did NMR at A level these days, but welcome and bring on your questions.
  15. Review requested

    You have asked for comments on the paper. Reading it I have some difficulty discerning exactly what it is you are interpreting. You should certainly spell this out at the beginning. Your comparison of Classical v Quantum including when to use which only covers cases selected to support your case. Other situations and considerations dshould be visited/included. For example the QM solution for the translational energy of an isolated molecule in a rectangular box a x b x c is [math]{\varepsilon _{translation}} = \frac{{{h^2}}}{{8M}}\left[ {{{\left( {\frac{{{n_x}}}{a}} \right)}^2} + {{\left( {\frac{{{n_y}}}{b}} \right)}^2} + {{\left( {\frac{{{n_z}}}{c}} \right)}^2}} \right][/math] Where n is restricted to integer values. which is much more complicated than the classical version [math]{\varepsilon _{translation}} = \frac{{M{v^2}}}{2}[/math] Furthermore there are a very large number of very closely spaced levels in the QM solution, clustered around the classical value. So simplicity suggests the classical calculation wins hands down.