studiot

Well well well, I pause to have lunch and go to Tescos and you have stopped talking to me again.

I thought so. You said you are an engine mechanic - a very respectable trade I know such people who have many innate skils I don't possess. They find it easy to for instance dissemble, fix and reassemble aBorg-Warner auto box whilst I know from personal experience of much simpler mechanics that I would struggle for days and probably not succeed with a B-W. However you anser brings us to appreciating the difference between power and energy. I have assumed you know this. Total energy (you have a total energy meter ?) used to keep the waterbath temperature constant for 15 minutes. Do you think 15 minutes is enough ? I don't. So over a longer period you can measure the energy to maintain that waterbath temperature. So what ? How do you know what proportion of that input actually goes into the working fluid ? And over that time how many cycles has you engine completed ?

Thank you, but that wasn't what I asked you. I asked you how you measure this supposed energy input to the working fluid. Not guesswork thank you.

Thank you, but how do you know ? You can't just pick an arbitrary figure out of the air and say I will put in 500kJ of energy. You are constrained by the characteristics of the system. You can measure and adjust temperature, pressure, and perhaps volume. You then need to calculate the energy (and entropy) interchanges from the 'observerables'. Talking of energy you said I posted the PV diagrams. Yes But I also posted the TS diagrams which are of great use to engineers and I use to answer the question "What is Entropy ?" The area of a PV diagram gives you energy and entropy was introduced originally to answer the question "We need a variable to go with temperature (an observable) in the same manner to also help us calculate energy. Plots of such varaible pairs are called 'indicator diagrams'.

Now that you are talking to me again, please remind me how you arrive at this figure of 500kJ supplied and what is it supplied to ? You do realise that the figure should only include energy added to the working fluid, nothing else ? Is this 500kJ over one cycle or what ?

We need more information. A sketch would be useful. You say a water tunnel. Is it running full ? If so what happens at the divergent section ?

Well I don't agree with either of you. In my view the opening post itself was clear enough, although I will accept any clarification by exchemist as to what he actually meant. I understood it to mean that: An article was published that declared in exactly these words "all knowledge is..." In my dictionary all knowledge includes scientific knowledge, including established facts such as Pythagoras' theorem. The article further states that political correctness is being applied to a particular course in a scientific subject, to whit Chemistry. exchemist appears to me to be asking if this is sensible (science) and providing his opinion that this situation is 'bonkers' I agree with him. In extending these simple observations to the countries and places where they speak different languages I respectfully suggest that both CharonY and Arete are the ones who have 'missed the point'. In particular the question of those who do not speak English is a red herring. Said person must speak his or her own language and the exam in his or her country will not be in English but in his or her own language. So why should they not pass the exam ? No, I would not expect them to come to an English speaking country and take the exam in English and pass. Would you ? Did you read the words 'perhaps we should' at the beginning of my sentence indicating Swiftesque irony ?

Fly though a cloud ? No, the body was made of balsa wood. The twin engines were made of metal and I presume the fuel tanks and lines.

Forgive me but I thought Mendeleev's original wrtings were in a mixture of Cyrillic for the text and Latin for the symbols as most of then known elements had Latin names.

Please give me strength. Go back to the two correct things you said which were 1) The air density inside the balloon is lower than the air density outside. 2) The air pressure inside the balloon is greater than the air pressure outside. ( But - my comment - this cannot be true at the opening or the higher pressure air would simply exit the balloon. This is why the given analysis sets the pressure at the bottom to be equal inside and outside ). Now consider a Montgolfier design; a ball shape with say the bottom 40% cut away to form the hot air entry part. The remaining of the lower hemisphere wiil be curved in such a way as for the higher pressure at the bottom to push down harder on it than the lower pressure pushes upwards further up. At the equator of course the net force is horizontal inside the balloon.

So you are claiming that a pure tension structure made of flexible fabric can support compression ?

I fail to see the relevancy of this to either of my comments. In particular would I be considered racist if I reported a black precipitate on passing hydrogen sulphide through copper sulphate solution ?

The Montgolfier shape is not the only possibility. Cylindrical hot air balloons work perfectly well too. What, by the way, is the point of pushing up on fabric at the bottom ? It will simply buckle or rumple under even the slightest push. It is vital to maintain tension in the skin of any balloon, open or closed. There is even a discussion of this in the article I posted. What a pity you don't like it because it is a nice piece of uncomplicated mechanics that is not often taught these days.

Make that check out to studiot in sterling please. Did you not read the associated text. Only the Carnot includes adiabats

All the basics necessary to compare the stirling (Ghideon please note correct spellung - sterling refers to money, gold and silver) cycle with the carnot cycle are in this excellent extract. It also provides conventional labelling to aid common discussion.

The most successful warplane of all time was made from wood. I know that's dead, but still it's worth mentioning.

I must say I fail to see what is subjective about the result of adding silver nitrate solution to sodium chloride solution. Perhaps we should ban such experiments since the majority of salts are white so white precipitates (if any at all) will be in the majority.

So what does the 'force of high pressure' act on considering the bottom of the hot air balloon is open oh wise one ? To make it quite plain it has no bottom.

No my decision is final in all cases.

I think the OP should be the judge of what they want or don't want, not you. In fact this text contains nothing more than can be found on the lower secondary school syllabus (GCSE in the UK). The reason that the pressure at the bottom equals atmospheric is that a hot air balloon is not sealed. There is a hole at the bottom so the pressure in the balloon must equal the pressure outside. This restriction is not necessary for a sealed balloon which can be at considerably higher pressure all round and considered as a rigid object for analysis purposes. It does show (without PHD level stuff) that there is a lift force pushing up on the inside of the upper part of the balloon. It doesn't mention this in the article but this force is not applied at the 'centre of bouyancy' , which is where the bouyancy force acts and so is important in considering the stability of the system - something I chose not not mention before. The textbook deals with equilibrium and centre of bouyancy elsewhere and I thought that a subject beyond this thread.

Thank you for bringing S Constructivism to my attention. Looking it up on Wikipedia it certainly does not embrace all scientific knowledge, let alone all other types of knowledge. In fact it seems very limited in its scope, far more so than exchemist's original quote (why did you not acknowledge it ? I had to waste precious time finding it in the thread.) . So I would say it was a fair attempt at noting that human observations tend to be some way from truly objective, despite our best efforts to the contrary. So it is always refreshing to see someone doing his or her best to act objectively.

Well done you have the right of it. +1 A hot air balloon will only stay inflated of the internal pressure is greater than the external pressure, otherwise it will collapse. I'm sory but this analysis is just plain inadequate. Here is a standard analysis of the subject @Saber please ask if you need anything further.

I still don't see any reply to my comments, which is a pity because you are travelling down the wrong path, pulling everybody with you. The outline scheme of though in analysing the relativity of the light clock runs as follow. The light clock is a self contained unit the output of which is not tracking the light path but a 1 second 'tick'. This tick measures 1 second when compared against the tick used by the stationary observer's ie the two clocks stationary are side by side. When the clock (and it is the whole clock not part of it) is in motion relative to the stationary observer, the observer receives signals of the number of ticks on the moving clock. When he times those ticks using his own clock he finds that they are longer than those of his own clock. This difference is calculated by relativity using distance information derived from the moving clock's motion. This is why others have said the primary observation is time dilation here. Incidentally you have been stridently claiming that the angle of incidence within the clock does not vary. This is not observationally true. The correct analysis, backed up by experiment, is not normally taught in elementary Special Relativity and leads to a formula for transforming between the angles of incidence observed by a stationary observer, θ, and by a moving observer θ', which are different, just as with the time ticks. The invariant in this case is the number of ticks. [math]\cos \theta = \frac{{\cos \theta ' + \frac{v}{c}}}{{1 + \frac{v}{c}\cos \theta '}}[/math] This formula is also associated with observed frequency changes to the light, known as the radia and the transverse doppler effects.

Good question. +1 Think carefully about your definition of bouyancy force.

That's exactly what is shown on the graphs I posted. What I actually said was the The absorbtion coefficient of the big carbon dioxide peak is shown on the first graph is shown to be at least two orders of magnitude, (nearly 3) greater than the 15 micron one.