studiot

Read here about phonons. http://www-sp.phy.cam.ac.uk/~wa14/camonly/statistical/Lecture13.pdf

It is not recommended to connect batteries in parallel because special (=expensive, bulky and power dissipative) circuitry is required to equalise them in use. It is, however possible and done on occasion, usually in fixed locations (eg remote radio transmitting stations), where large banks of accumulators are required. An accumulator (eg a car battery) has its cells in series, not in parallel. That is how you can obtain 6 volts, 12 volts or 24 volts as standard in this type. Battery powered portable equipment normally has its voltage supply made up from several cylindrical batteries connected in series. Picture 2 here clearly shows the series connection. http://www.progressivedyn.com/battery_basics.html

Hello Iwonderaboutthings, I'm glad you said "why do calculations need to be balanced" not "why do equations need to be balanced" You clearly appreciated the difference. Calculations refer to a process. Often you start with one (or more) things and end up with something else, as you examples ably showed. So for instance % - You start with two things profit and principal and as a result of the process end up with %Profit. There is nothing balanced about this. So the simple answer is calculations do not need to 'balance'. On the other hand, when referring to equations, swansont gave a hint when noting that something may be preserved in an equation. This something may be the subject itself of the equation or it may be a property of the the subjects. That depends upon the nature of the equation. We should also note some things about equations. Chemical equations may have a preserved property (eg number of atoms) as Oophiolite was saying - or they may not. For instance the general chemical equation Acid plus base = salt plus water need not 'balance' ie the subject of balance need not be considered for the equation to make sense. This equation refers to a process as I noted above. Chemists often recognise this by using an arrow symbol in place of the = sign we read the word 'makes' instead of equals. However timo is not quite correct in stating that an equality is the same as an identity. Consider the two equations 3x2+8x+6 = 2x2+5x+4 3x2+8x+6 = (x2+4x+1) + (2x2+4x+5) The first is only true for certain values of x - This is an equation. The second is true whatever the value of x - This is an identity. The first equation does not 'balance' there are not the same number of x squareds, x's and constants on each side (I mean the coefficients are not the same). Or as swansont says nothing is preserved. We can execute a process on this equation to 'solve' it for the particular values of x for which it is true. The second equation does balance since the collected coefficients are the same on both sides. However we cannot now apply our solution process to this expression. You cannot 'solve' an identity. In physics consider the forces acting on a body. There is no requirement for them to be in balance. If they are in balance there is no resultant and the body is in equilibrium. So we apply the laws of equilibrium or statics. If there is a resultant this is a condition that the body is not in equilibrium ie it is accelerating. Then we apply the laws of dynamics. So in the physics case balance is used as a test of equilibrium.

The described system is quite interesting and is not a simple feedback system. It is, in fact, a form of multivibrator, one view of which is that it is not one but two cross coupled feedback systems. With the right time constants you can make this system into a chaotic one. go well

Norman Rockwell, one of my heroes.

Sure it does. The point about a determinate outcome is that it is the same every time the experiment is repeated under the same conditions. The point about an indeterminate outcome is that it may be the same every time, it may be differeent each time. Further with a tristate logic chip the output may enter a state not recognised by succeeding circuitry.

Actually it doesn't. In a dichotomy the outcomes are defined are one of two possibilities, there are no other alternatives. In a trichotomy the outcomes are defined as being one of three possibilities, again there are no other alternatives. In trisate logic there is an indeterminate outcome available. There is still a defined binary input. The point of indeterminate is that it is not determinate.

You should certainly talk this subject over with your teachers as you have got yourself a bit muddled up. Yes 1 calorie is the amount of energy required to raise one gram of liquid water 1 degree centigrade. Note the emphasis on liquid. It applies from 0C to 99C. If you raise some water at 100C to 101C it is no longer liquid. So to raise 56 grams of water from 25C to 35C would require 56 times (35-25) = 560 calories. But water can also exist as a solid or gas (ice or steam). When water changes from solid to liquid or liquid to gas or back again, there is no change in temperature until the whole sample has changed. This emphasised bit is very important since it means that there is no heat energy involved due to temperature change. However it still takes energy to change the state of the water. And this energy is much larger per gram, than the amount needed to change the liquid by 1 degree. This energy is called latent heat. For the change from solid to liquid at it is called the latent heat of fusion. For ice at 0C to water at 0C this is 80cals/gm/C For the change from liquid to gas it is called the latent heat of evaporation. For water at 100C to water vapour at 100C it is 541cals/gm/C You can see that it take more energy to boil than to melt a substance. As to the second part of you question, Yes your have started correctly, it takes 75 calories to raise 1gram of liquid water from 25C to 1 grma of liquid water at 100C, it then takes an additional 541 calories to turn this into gas. So the total is 75 + 541 = 616 calories. This is slightly higher than your book figure. Finally about the hydrogen bonding. Water has unusual properties due to hydrogen bonding. The melting and boiling points are higher than for the next larger molecule in the periodic table. Normally it is the other way round since it atakes more energy to move a large molecule around. Water is hydrogen oxide and is a liquid at normal temperatures. Hydrogen sulphide is a gas at normal temperatures, which means it has a lower boiling point. Does this help?

You certainly named them, but what makes you think they have universal applicability? I showed you a system to which they do not apply.

My windows2000 mathcad gets the same eignvalues for A as you do, but different ones for the transformed matrix. I get the three zeros again, your negative -0.66 and the complex conjugate pair. I think it was Euler had a method to make the complex pair equivalent to a two real values.

I said swansont was your man on this subject.

Exactly. What 'laws of logic' ? There is not an exclusive set!

Are you sure ? What about tristate or Kleene's logic? http://en.wikipedia.org/wiki/Three-valued_logic I do believe it was the Bard himself who said "There are more things, in Heaven and Earth, than Man has ever dreamed.

Yes I did read it and I may have missed something vital. If so I'm sorry and would be pleased for you to point this out. However I should correct one or two points where you may have misunderstood the article, it was rather short on detail. Firstly the article states "the vast majority of the electromagnetic emissions would be in the hard ultraviolet range" You seem to have translated that into the 'majority of the energy', which the article did not say. Further neutron emissions are not electromagnetic emissions. further they are not, in themselves radioactive. Yes using the energy of the nuclear fire to megaheat exhaust propulsion gas is a desireable aim. The article has no details of the fission reactor itself or its control or shielding. Further to develop and maintain the intense magnetic fields you would require a significant electrical generator (presumably powered by nuclear energy) All of this add significant weight to the beast. It's sort of like the fact the the internal combustion engine need to devert some of its power to the oil pump, the water pump, the fuel pump and so on. Nevertheless the it is worth pursuing and re-examining the idea from time to time as new materials and techniques become available. go well

Fission produces a great many neutrons. The fissile material in your linked reactor is uranium hexflouride, which is subject to all the factors I outlined earlier. The point is that fission also produces a great deal of heat. In your reactor this passes through a quartz wall and heats a propulsion gas. Are you suggesting magnetic fields to direct this ionised gas? That is sensible. However you also need a generator to create the electric current to generate the magnetic fields. Would this fit comfortably on board the rocket? Further, at the end of the day, you also have to control your fission reactor in the normal manner.

Sorry I missed that Well, fusion reactions involve much simpler particles than fission and these have the advantage of being charged so we can use the relationship between electricity and magnetism to exert real containment forces on the participating particles. Further we have a relatively few particles involved, undiluted by non participating particles so the confinement space is much smaller. Fission, on the other hand has an abundance of uncharged neutrons to control. These, of course, are not amenable to magnetic fields. Further the fraction of participating or reactive particles in even a refined mass of fissile material, is quite low. I would suggest that with his background, Swansont is your man for this.

Bohr orbits are subject to the equation [math]n\lambda [/math] = [math]2\pi {r_n}[/math] n = 1,2,3,4.... Where rn denotes the radius of the orbit which contains n wavelengths. Bohr's theory only had one quantum number, n So if n = 10 the circumference of the orbit circle contains 10 wavelengths. Does this help? gosh why is latex so difficult on this site?

Here was an early attempt at this http://en.wikipedia.org/wiki/ZETA_(fusion_reactor) Here is a later one http://en.wikipedia.org/wiki/Tokamak

What do the quantities PV and TS represent? Hint they are both (diferent) forms of energy transferred during a thermodynamic process. The short answer is you can't directly But PV and TS are ways of calculating of a term in the First Law. This gives you an indirect way obtaining one from the other. Think about the freezing/melting example we worked through in your previous thread. Can you draw the PV and TS diagrams for this process in a complete cycle?

No, but you made a claim so kindly have the good grace as a styled house resident chemistry expert to explain.

Yes I agree there is a good deal of politically correct 'recycling' going on. However your comparison is unfair. Option 1) Make new, no recycling. You have not added in the energy or $ cost of dealing with the resulting discard Option 2) Recycle at greater energy / $ cost but no discard costs involved. Here is an interesting quote form John Le Carre

I can't believe that the current is provided by mving Ag+ ions. Just think how massive they are compared to electrons and the effect of piling billions of them up at one end of the conductor, which is what you are saying by saying that they conduct the current.

I have had a rethink about my first answer, which was too hasty. My apologies. The terms exothermic and endothermic refer specifically to the generation or absorption of energy as heat by the process. Other forms of energy change (eg work) are not included. Nor are entropy changes included. To account for this further thermodynamic functions called free energy have been defined. The free energy may be negative because heat is evolved in an exothermic reaction (eg combustion) or it may be negative because of a large entropy change which outweighs the positive heat input in an endothermic process (eg vapourisation) This, I think, is what was meant by an energetically favourable reaction. We can expand on this further if you wish. Have you heard of Gibbs or Helmholtz free energy? Please note that just because a reaction is energetically favourable it does not mean it will necessarily occur, because of what I said before about activation energy. For instance you can have a container of hydrogen and oxygen without them reacting. But apply a spark!

I'm sorry that you are so hung up on bashing quantum mechanics. I haven't employed it once. All I said was that the qualities you required could be attributed to a stream or flux of 'something' that did not have to be waves (or particles). Turnips could very well 'go in the other direction', so could any 'flux'. Much of the mechanics I deal with does not enquire as to the nature of the 'elements' it attributes certain properties and develops a model in terms of these. And these models ( eg fluid mechanics) are extremely successful at what they do. I also observed that every time I asked about a property that was specific to waves and not shared with other entities you fell back on the 'flux' idea, as does Little. Anyway I am still preparing my presentation. go well

But