studiot

+1

Hello, phi perhaps you should contact the man who built the inverted triple pendulum balancer in 1995. It doesn't look too expensive (perhaps a double malt?)

I didn't see the December '16 thread referred to in the outset posts, but you have subtitled this thread ' 3 possibilities'. That brings me to an interesting spin off point about this. The coin toss is about the simplest random process we have. We usually accept that we have equal probabilities of 0.5 and 0.5 for each side. If we step up one level of complexity to the standard die of six sides we have equal probabilities for each of six sides. But introducing the die introduces something not available witht the simple coin toss. We can conside the probability of a number less than or equal to 3 (other other combination). This probability is also 0.5. Now that we have understood that we can create new categories of event by combining outcomes we can look again at the coin toss. We can now consider the probability of 'anything else happening at all' This is a very useful step forward as we can now have 3 outcomes Heads, Tails, Anything Else. If we can show that the probability of anything else is below the radar, ie insignificant, we can go safely return to our unbiased coin. Evidence has been presented to suggest that the probability of anything else is less than .0002. Do you think this is significant?

Good answer +1 There is one thing about these devices, they are indiscriminate. So it is difficult to be certain what you are pointing them at. You have to be careful the received reflection (OP note not refraction) is actually from the object of interest. This is where dedicated reflector types have the advantage, but obviously you have to be able to access the target.

The site is The British Broadcasting Corporation. Much of their output is also available on youtube.

Thank you for thinking about my questions, but please reply ouside the quote as it makes copnversation easier and more manageable that way. I'll take your second answer first. No I did not say work was done, you did and I quoted where you said it in my post #8 So I asked you about it. What you say is not wrong it is just not complete, because there is a difference between heat and work. That was why I asked the first question because there are other aspects to energy besides work and heat is one of them. For example energy in the form of heat is added or removed to cause a phase change, but no work is done. This is called the latent heat. Even in the purely mechanical world there is a theorem: "No work is done when a system of forces in equilibrium move their point of application." This is known as the first theorem of Virtual Work and is much used in certain forms of mechanics and as a test for equilibrium.

There is a series of programmes on BBC television http://www.bbc.co.uk/programmes/b08ghp29 A couple of the cases were very similar to what you are describing, where sense information gets scrambled, some are even more bizare. I don't know what you can access online but Dr Weston's programmes are also available on DVD. Many of the cases were from the US if you are there. Perhaps you can interest a researcher in your friend's case.

Was this a serious question or just idle daydreaming? One of the most basic and elementary things we learn in Chemistry is the classification of 'substances' into pure compounds and mixtures. Do you understand this and further what the terms homogeneous and amorphous mean? Analytical Chemistry is a huge branch of the subject so perhaps if you would put some effort into explaining what you really mean someone might be able to help you. +1 to sensei for his guess as to your intentions.

Happy book hunting, but be aware that these are older books, (mid 20th century), commensurate with your area of interest and techniques you might have available to you as an amateur.

Who says modern science arose in Europe or was kicked off by the renaissance? I suggest that the earliest humans discovered and used the scientific method (better than some here I might add) I further suggest that earlier peoples put it to different uses than the more recent Europeans. And that these uses were conditioned by the times of their use. We just need to recognise the differences. Comparing Neolithic Science and Modern Science, consider a flint arrow head. Modern Man looks at this and sees a 'bulb of percussion' and striking ripples. He sees a certain Moh's hardness and so on. By the time neolithic man was making this arrowhead, he must have already used the scientific method several times. Firstly to be making an arrowhead he must have invented the bow and arrow. So he must have understood enough elasticity from his point of view to have tested different woods for springiness and hides as strings. He would also have previously established that flint is a far better material than say sandstone for the job. That is why modern Man does not dig up sandstone arrowheads. Roll on many tens of thousands of years, and further scientific developments such as the discovery of a marvellous new material for arrowheads. Bronze. By this time population density had increased and Man needed to develop skills in new directions - Social Sciences. He had to learn to live together in significant sized settlements. So much development at that time concerned this aspect of developemental history. Hammurabi's code was a prime example. But all the ancients from then on were hindered from turning down a modern path right up to the pre-renaissance when the 3 centuries between Fibonnaci and Cardano saw the development of the full number palce system - our decimal system. Science needs Mathematics and this is where our version started. Previous mathematics had all been unrelated 'cookbook' techniques, like the instructions for arrow making. Specifically aimed at solving a particular problem or meeting a particular need.

Roger, your posts are getting better. I am regrading them from wildly inaccurate to incomplete and a bit confused. Keep the progress up. Two questions for you to think about. Why do you think that, since it was first stated, the First Law of Thermodynamics makes a distinction between work and heat transfer, if all energy involves work? You say that energy is transferred to do work. In what form was energy before it was transferred?

You might like to seek out this book Electron Physics and Technology by Thomson and Callick (note not JJ Thompson with a p) English Universities Press (So sad they were shut down) Chaper 5 Gaseous conduction is of particular interest. But the whole book is a mine uf useful theoretical and practical information from materials, to pumps to vacuum generators to HV pulse generators. Also very relevant is Advances in High Voltage Insulation and Arc Interruption by Maller and Naidu Pergammon

For the benefit of whoever liked my previous post the thing about Thevenin is that it replaces the whole circuit to the left of the load between point A and B with a contant voltage generator in series with a resistor. The purpose of the CV generator is to provide the voltage that is actually applied across AB by the missing (replaced) circuit. The value of this voltage generator is called the Thevenin voltage. The Thevenin voltage is not the voltage across both the CV generator and the series resistor, it is just the value of the CV generator. The purpose of the resistor is to take account the loading effect of the load so in this case Vth is the 8 volts that appears across AB without the load as given by the potential divider ie 4/5 of the 10 volts across the 4k resistor in series with a 1k resistor. In the real real circuit the connection of the load 20k resistor on the right hand side of AB is in parallel with the 4k resistor so it reduce the the actual voltage across AB in the actual complete circuit below 8 volts. Thus Rth is added to provide the Thevenin circuit with the 8 volts divided between Rth and the 20k load. FYI Norton analysis works in exactly the same way except that a constant current generator with a parallel resistor is used.

The title of this thread looks like a homework question so I am going to treat it as such. Both gasand steam turbines areheat engines. That is they interconvert between heat and work - in this case they output (useful) work from an input of heat. The thermodynamic efficiency of all heat engines depends mainly upon the temperature difference between the reservoirs. Other measures of efficiency are available such as comapring the energy in the fuel with the output but this is not the thermodynamic efficiency. So your first task must be to decide which efficiency measure you are discussing. Air plus fuel can be heated to a higher temperature than steam so has an inherently higher work generation. Latent heat for steam does not thus enter the calculation. However the gas turbine work also has to power the air compressor which work is then unavailable to output. So you need to look at the cycles for steam and gas turbines - I suspect that is where the diagrams come in and they want you to discuss the differences between the steam cycle and the gas turbine cycle. The Rankine cycle or perhaps the simpler carnot is appropriate to the steam cycle The constant pressure or again perhaps the carnot gas cycle is appropriate for the gas turbine. Here is the sort of diagram I am referring to for thye Rankine cycle.

No, just don't go there. Having got that out of the way your other two questions are entirely reasonable, but very difficult to pin down. As already noted by others, energy is a property, but you might reasonably ask a property of what? Well energy is a property possessed by a system by virtue of its configuration. Generally there is an energy change associated with a change to that configuration. We observe this in many ways A ball rolls off a table and falls to the floor A kettle of water boils to produce steam A fast radiation particle precipitates a droplet trail in a cloud chamber Sodium carbonate and calcium chloride solutions precipitate calcium carbonate solid particles when they are mixed. The thickness of the brake pads in your car (I hope they are finer than 36 grit) decreases with use. It is also said to be the capacity of a system to perform work. This is the definition where energy is usually first introduced in elementary Physics. But then we go on to talk of available and unavailable energy (Clausius and Maxwell) in more advanced work and then zero point energy (Plank) in even more advanced work. This shows that not all energy can be used to perform work, even in theory. So where are we? Well the answer raises more questions than it answers. And we have yet to define a system, or configuration. I can't say the exact number, partly because there are so many and partly because there is some overlap in usage. Expressions for energy appear in pretty well all branches of physical science, each one tailored for use in its particular area. A great deal of work over several centuries has taken place to make sure that they are all consistent today.

A small observation (not a criticism). All the choices so far presented seem to be of the 'all or nothing variety' for instance Perhaps you were actually taking your girlfriend for a Chinese meal and the choice was not jacket or no jacket but jacket or chinese because you had money in your pocket / on your credit card for one and not the other. I chose to go to Scotland on my last holiday, not Tibet. In this case I was spending time, not money as holiday time is limited, though I could have afforded the money for both.

Firstly you have written Rth as 8k in red, which is 10 times too much. Edit I see you have .8 k sorry - a piece of advice never omit the leading zero before the decimal point. Rth = 0.8k Secondly they say (correctly) exactly how the thevenin voltage is calculated in their text. Remove the load (20k in this case) Use simpler circuit laws, eg potential divider (in this case), KCL, KVL etc on what is left of the circuit to determine the open circuit voltage between the terminals of interest (A, B in this case). Just follow that proceedure on a couple of examples to get the hang of it. It seems a bit silly on such a simple example, try it on a more complicated one.

This is good https://www.amazon.co.uk/Chemistry-Palgrave-Foundations-Rob-Lewis/dp/0230291821 and this is good https://www.amazon.co.uk/General-Chemistry-Principles-Modern-Applications/dp/0132064529 After these you will need to look for books in specific chemistry subject areas eg organic chemistry, analytical chemistry etc. One more for the road for those who are cramming for an exam bu reading for love of the subject. https://www.amazon.co.uk/Atkins-Molecules-Peter/dp/0521535360

CPC-farnell are a regular supplier of mine, but I didn't know what wattage you needed. I suggest you look at industrial ceramic heaters in Screwfix or MachineMart. Just no-nonsense power. However I claim my share of the chestnuts.

http://cpc.farnell.com/clarke-international/6920262/devil-350-2-4kw-ceramic-heater/dp/HG00946?ost=ceramic+heaters&searchView=table&iscrfnonsku=false&ddkey=http%3Aen-CPC%2FCPC_United_Kingdom%2Fsearch You mean like this?

I was born in England and consequently my first language is English. As such I am quite accustomed to words have several meanings and people restricting these meanings to a particular one or part of one for the purposes of discussion. I am also accustomed to this in the narrower ambit of scientific and technical English, where it is even more common to prevent misinterpretation. So for instance I might start a lecture by defining a differential as a particular system of gearing one finds in many vehicles. Others might use quite a different definition. Scienceforums is similarly entitled under both the usage practice of common and technical English to make such a restriction, quite apart from the modern belief that business can mangle our once great language as it pleases.

This is a fair question that does not seem to have been answered. It is called kissing contact.

I really don't understand what you mean by this, but I hope you have not taken offence. Certainly none was intended so I apologise if you felt offended in any way. I was hoping to cheer people up in this thread - perhaps I would be better keeping out of religion, I usually do. Meanwhile you don't seem to be visiting the post I drew up especially for you in your electrical engineering thread.

Galveston is a long way to go for Sunday worship, I'd probably be late.

Gosh what a jumbled up question. Is this homework or a test that you require such an urgent answer you have to leave before anyone can answer? It certainly does not belong in modern and theoretical physics. OK so release of energy when you walk, and presumably when travel by the other means stated as well. Released is not really the correct term but we can discuss this if you ever return. Conservation of energy requires that energy is generated somewhere during the activity and transferred to the support surface, by work being done on the support surface (mechanical energy transfer) or by temperature difference between the traveller and the support surface (heat energy transfer). Friction will only do work if there is slippage or sideways movement between the contact surfaces. Work is done in deforming both contact surfaces and transferred to the support surface as strain energy. You have not offered the examples of cutting or grinding tools, but work will also be done in cleaving the support material. Finally, as delta1212 observes, impact work will be done if there is impact rather than smooth rolling. Momentum is not work or energy.