Jump to content


Senior Members
  • Content Count

  • Joined

  • Last visited

  • Days Won


Everything posted by studiot

  1. And I'm sorry to point out that you seem to me to be bent on finding fault with my attempts to explain my principle point to you, rather than understanding the point itself. As I understand your thesis here, you are proposing that there is one and only one Law or rule that applies to your partitions, that due to Boltzman. However it remains your responsibility to support your thesis so please explain the anomalous first ionisation energies of Nitrogen, Phosphorus and Arsenic in terms of your proposition.
  2. This is the unaswered question. +1 Consider a system of molecules in some volume. Unless both molecules have the same velocity they do not have the same kinetic energy and therefore the internal energy is not evenly distributed between the molecules (maximum entropy). So the famous 'hot death' of the universe must be a static (as in unchanging) situation from the point of view of maximum entropy. But this view ignores the fact there are twin drivers in the thermodynamic world that often pull in opposite directions. The principle of minimum energy can be used to devise a system that will oscillate indefinitely at fixed (maximum) entropy.
  3. Sensei said it better than the website I linked to. Sodium Chloride MP 801oC Sodium MP 98oC BP 883oC Chlorine BP -34oC So if you just 'heat it in a crucible' to 800oC + you will drive off the chlorine as a rapidly expanding highly corrosive gas. The sodium will be just liquid but close to its boiling point so will also be exterting substantial vapour pressure. So you will need more than just a crucible in a furnace. My comment was about safety.
  4. Crucible material is not your only problem
  5. studiot


    The book Non- Euclidian Geometry by Manning was originally published in 1901. Here is the passage. I did actually try adding non euclidian and geometry, and boundary curves but can't remember if I just included mathematics. Also tried Wolfram but no luck there. Thankfully the theorory of horcycles appears in my Dan Pedoe's Geometry, a Comprehensive Course. Thanks again to you both.
  6. Thank you for considering my comments. I'm sorry my analogy was not clear enough for you to understand. So try this one instead. Both chess and draughts are played on the same board. But they are very different games with very different rules, and different end results. Events can happen in chess that cannot happen in draughts and vice versa. The same can be said of the partitions of your master set. This carries over to the other part of your answer. There are umpteen relationships in physics where something is proportional to something else. And very often the contant of proportionality carries the units as in strain (a dimensionless quantity) is proportional to stress. But that does not mean we can disregard the constant and say therefore stress and strain are the same as thermodynamic entropies. Otherwise you could model one on the other, but if you tried you would obtain conflicting results, just as if you tried to play chess with a draughts set or vice versa. Information entropy and Thermodynamic entropy are not the same, or subject to the same laws (as in the rules of chess and draughts).
  7. studiot


    Many thanks +1 I will see if this fits the article I have.
  8. studiot


    Does anyone have any referencs to Oricycles ? I can't seem to find any. This is a (non Euclidian) geometrical question.
  9. Didn't you miss something out here? Thermodynamic entropy has to have units of energy per degree of temperature. Other entropies, such as your runinations (pun intended) will have different units. In a block of flats there is (or should be) a one-to-one between the pigeonhole letter boxes at the entrance and the flats and their organisational structure. But would you rather live in a pigeonhole or flat? They are not the same.
  10. That was part 1 - it was taking so long I though I'd split it. Part 2 is a bit less mathematical, but I'm gald to see you can cope with partial diffs.
  11. Yes you are right thank you, though I thought I had spotted it and fixed it once. I hate LaTex.
  12. Like it +1 @Nedcim I hope this helpsyou.
  13. Yes and how many objects is 'objects' ? There must be more than one. But how many objects are there in a free body diagram ? Just one. Understanding this is the key to it all, as Ghideon so nicely told you three pages ago. and could you repair this English please / I do not understand the underlined bit. At the end I can see that it says that if A exerts a force on B then B exerts a force on A and I agree with that (as does everybody else).
  14. Part 1 The analysis if the Joule-Thompson or Joule-Kelvin flow or throttling is interesting because it demonstrates so many points in a successful thermodynamic analysis. Appropriate system description Distinction from similar systems Identification of appropriate variables Correct application of states Distinction between the fundamental laws and the equations of state and their application JT flow is a continuous steady state process. The system is not isolated or necessarily closed, but may be treated as quasi-closed but suitable choice of variables. It cannot be considered as closed, for instance, if we consider a 'control volume' approach, common in flow processes, since one of our chosen variables (volume) varies. By contrast, the Joule effect is a one off or one shot expansion of an isolated system. So to start the analysis here is a diagram. 1 mass unit eg 1 mole of gas within the flow enters the left chamber between adiabatic walls and equilibrates to the V1, P1, T1 and E1. Since P1 > P2 the flow takes this 1 mole through the porous plug into the right hand chamber where it equilibrates to V2, P2, T2 and E2. The 'system' is just this 1 mole of gs, not the whole flow. The system thus passes from state1 to state 2. The First Law can thus be applied to the change. Since the process is adiabatic, q = 0 and the work done at each state is PV work. E2 - E1 = P1V1 - P2V2 since the system expands and does negative work. Rearranging gives E2 + P2V2 = E1 + P1V1 But E + PV = H or enthalpy. So the process is one of constant enthalpy or ΔH = 0. Note this is unlike ΔE which is not zero. Since ΔE is not zero, P1V1 is not equal to P2V2 More of this later. Since H is a state variable and ΔH = 0 [math]dH = 0 = {\left( {\frac{{\partial H}}{{\partial T}}} \right)_P}dT + {\left( {\frac{{\partial H}}{{\partial P}}} \right)_T}dP[/math] [math]{\left( {\frac{{\partial H}}{{\partial T}}} \right)_P}dT = - {\left( {\frac{{\partial H}}{{\partial P}}} \right)_T}dP[/math] [math]{\left( {\frac{{\partial T}}{{\partial P}}} \right)_H} = - \frac{{{{\left( {\frac{{\partial H}}{{\partial P}}} \right)}_T}}}{{{{\left( {\frac{{\partial H}}{{\partial T}}} \right)}_P}}}[/math] Where [math]{\left( {\frac{{\partial T}}{{\partial P}}} \right)_H}[/math] is defined as the Joule-Thompson coefficient, μ, However we actually want our equation to contain measurable quantities to be useful so using [math]H = E + PV[/math] again [math]dH = PdV + VdP + dE[/math] [math]0 = TdS - PdV - dE[/math] add previous 2 equations [math]dH = Tds + VdP[/math] divide by dP at constant temperature [math]{\left( {\frac{{\partial H}}{{\partial P}}} \right)_T} = T{\left( {\frac{{\partial S}}{{\partial P}}} \right)_T}dP + V[/math] But [math]{\left( {\frac{{\partial S}}{{\partial P}}} \right)_T} = - {\left( {\frac{{\partial V}}{{\partial T}}} \right)_P}[/math] so [math]V = T{\left( {\frac{{\partial V}}{{\partial T}}} \right)_P} + {\left( {\frac{{\partial H}}{{\partial P}}} \right)_T}[/math] combining this with our fraction for μ we have [math]\mu = {\left( {\frac{{\partial T}}{{\partial P}}} \right)_H} = \frac{{T{{\left( {\frac{{\partial V}}{{\partial T}}} \right)}_P} - V}}{{{C_P}}}[/math] Which give a practical form with quantities that can be measured. [math]\Delta T = \frac{{T{{\left( {\frac{{\partial V}}{{\partial T}}} \right)}_P} - V}}{{{C_P}}}\Delta P[/math] Joule and Thompson found that the change in temperature is proportional to the change in pressure for a range of temperature restircted to the vicinity of T. The next stage is to introduce the second law and the connection between different equations of state and their meanings or implications. Edit I think I've ironed out all the latex now but please report errors to the author.
  15. Yes I agree, Turing took one of the many steps along the development of IT, he did not invent the Von Neuman architecture (I wonder who did that ?) Although originally a theoretical mathematician, Turing was also practical as evidenced by rewriting the intensively theoretical Godel theorems into a practical (if gedanken) setting). But modern IT is about more than just about one thing. It draws together many disparate aspects of technical knowhow. But it is difficult to list the many who contributed to the drawing together of the many different threads without missing someone out, or how far back to go in engineering history. For instance what would the internet be like without the modern display screen ? Should we include the development of these or printers or printing itelf? Fax machine were first invented in 1843. What about control programs? Turing is credited with the introduction of 'the algorithm'. But Hollerith invented the punch card in 1884. You need The laws of combination logic (Boole, De Morgan) The implementation of these in machines (Babbage, Hollerith, Felt) Methods of communication between machines (Bell , Bain, Hertz, Marconi) The formation of 'words' of data from individual combinations. Standardisation of these words - the language (Bemer) Moving from mechanical to electromechanical to electronic implementations of data structures (Von Neuman) So here is my (draft) shortlist of the development, apologies for any omissions. Babbage (1791 - 1871) the analytical engine De Morgan (1806 - 1871) De Morgan's theorem. Boole (1815 - 1871) Boolean algebra Bain (1810 - 1877) the Fax machine Bell (1847 - 1922) The telegraph telephone Hollerith (1860 - 1921) punch cards Braun Berliner (1851 - 1929) microphone (inter machine communications) - 1876 Braun (1850 - 1918) cathode ray tube (inter machine communications) - 1897 Felt (1862 - 1930) Comptometer 1887 Von Neuman (1903 - 1957) Digital computer architecture. Bemer (1920 - 2004) Standardisation of digital words. 1961 Interestingly names beginning with the letter B predominate, perhaps that was Turing's crime - to start his name with the wrong letter.
  16. Pematurely is the wrong word. There is no shortage of (sustainable) energy, just a vast shortage of the political will to use it. Like some many socially worthwhile changes (e g water supply) it is just a question of engineering.
  17. That's only because the cops keep asking if you are old enough to smoke.
  18. Building machines to decode enigma seems pretty practical to me? However I thank the OP for asking the original question since it resulted in my finding out something I did not know about Alan. His main purely theoretical work, an early prediction of chaotic behaviour, resulted in the discovery of B-Z reaction in chemistry.
  19. Yes exactly. Absolutely not. Not even your textbook says this. Again this is not the case. Two forces, acting on different objects, cannot be 'in equilibrium. Only forces that act on the same object can be in equilibrium. Newton's third law is not about equilibrium. I think the key to understanding and getting it right is to start with a good diagram. and I am sorry to say that the diagram from your book is not a good diagram, for all it prettiness.
  20. Bob Bemer http://news.bbc.co.uk/1/hi/technology/3838845.stm
  21. Once again you are short on method statement. Some presentation of the results wouldn't go amiss either.
  22. Of course it helped. Although Richard Hamming is rightly credited with developing the organised structure for digital computing, Alan Turing must have known some of this since he was in at the beginning of digital machines, so must have known and used some of this. By organised structure I mean the combination of several digital units into data 'packets'. By digital I mean the use of a few definite values, not a continous spectrum of values.
  23. Actually though trivial in this case, and not a simple as the plain statement of static equilibrium F = W, the virtual work method has attraction in a similar situation. I was once challenged by a PhD specialist in electrodynamics (not here) how to derive the controlling equation for an electromagnet picking up a car in a scrapyard. When we compared solutions, his was 3 pages of advanced mathematics to avoid magnetic forces doing work, and mine was 3 lines long. (I haven't forgotten the thermodynamic question)
  24. Marvellous vegetable, the potato. It was one important factor that powered the development of 19 century America. If you ever visit Ireland, visit the American-Irish Folk museum. Lot's on the history of the potato there, including the cooking and nutritional values.
  25. I don't know if your factory makes moonshine or what from your potatoes but coincidentally the Times (26 May p7 ) reports that
  • Create New...

Important Information

We have placed cookies on your device to help make this website better. You can adjust your cookie settings, otherwise we'll assume you're okay to continue.