studiot

Well two issues that could concern humanity come to mind. Firstly the BBC state that it has implications for climate science. What are they? Secondly they state that the current pattern is the way it is because water flows down hill. I thought there was also a large thermal component to this which causes the worry that climate change will change the pattern of currents. But if the water is basically flowing into dips in gravity then will it not be more stable than previously thought?

Thanks, some discussion would also be appreciated.

http://www.bbc.co.uk/news/science-environment-30191584 It would be nice if anyone had a link to the (sea)horse's mouth on this.

Looking at the times of your last visit here, and looking back at your previous posts I find this is typical, You clearly don't wish to hold a discussion, which is the purpose of a discussion forum. You simply wish to preach prepared sermons rather than offer discussion, proof and reasoned argument. And when they are rumbled you resort to insult.

You either cannot or will not answer John's question about the electricity generator. To answer John's question you need to understand that he is talking about a different potential energy from the potential energy you keep mentioning. John is talking about total potential energy, which includes gravitational potential energy, but is not limited to that. A tethered helium ballon has at least one additional source of total potential energy besides gravitational. You are talking about gravitational potential energy alone. Given the above information can you prepare a cogent argument as to all the relevant energy interchanges that occur when we release the tether and the balloon rises?

Yes indeed and thrice now you have failed to answer since this is now the third time. Which is highly appropriate since ploy # 3 from the manual of tactics for trolls reads. "When faced with a question you cannot answer, do not try to answer just change the subject" Of course my post#112 was such a question. I have never disputed that there is descending air associated with heavier-than-air flight and indeed the combined posts by ccweb and myself explained the need for this fully along with the mechanism. What I do dispute is your interpretation of the laws of physics, cavalierly discarding some and cherry picking others to suit your self. Worse you even misapply them. You have linked to some nice photographs, without any proof or explanation that they show descending air, and still without answering the question "Where did it come from?" A further related question might be; "where is the centre of gravity of this descending air in relation to the plane?"

OK I said I'd post some more. I have tried to show things in diagrams and I am assuming normal distributions. Bignose will no doubt wish to generalise this if he comments again. If we go through my diagram, hopefully it will become clear. Most texts show a diagram like sketch A, but do not make it clear that there are two distributions in play, not one. And few show you the sequence sketch B through sketch F I cannot stress this enough. My sketch A refers to the distribution of all possible sample distributions. (of the size of sample we are taking) All the others refer to the population distribution. Unlike in your previous thread we either have the population mean and standard deviation or we are assuming it as H0 So in my example the population mean is postulated as being 8.0. So in this case the mean of all possible sample distributions should be the mean of the population, and we will take this as our null hypothesis and examine the errors that may arise if this is not true. This allows us to set the cut off points which are also called critical values. In my example they are 7.9 and 8.1 These cutoff points are where the acceptance criteria / decision rules I mentioned arise. If we take a sample and the mean of the values falls between 7.9 and 8.1 we accept the H0 Since H0 and H1 are mutually exclusive accepting H0 means rejecting H1 So we don't test for H1 That is our acceptance criterion is [math]7.9 \le {\mu _{sample}} \le 8.1[/math] Outside this acceptance range we reject H0 and the area of the tails gives us the probability of a TYPE I error This reappears in sketch D. OK so now we ask what happens if the population mean is not 8, because there is something wrong that requires action. In sketches B, C, D, E and F I have successively moves the population curve along the axis to show it in various positions in relation to the critical values I have projected down from above by the dashed lines. Note these have not moved from the original sample basis in sketch A So in sketch B if [math]{\mu _{pop}} = 7.7[/math] then the right hand tail only enters the acceptance region. That is there is a small probability that a sample drawn from this population could have a mean within the acceptance region. This only occurs for a small % of cases but if our sample mean lies between 7.9 and 8.1 we will (wrongly) accept it. This is a TYPE II error The area that this tail intrudes into the acceptance region yields the % or probability of this. This is the reason you were asking why a one tailed value was calculated in one of your examples In sketch C I have moved the population curve mean along the first critical point at 7.9 Now there is a considerable probability that a sample mean drawn from this population could fall within the acceptance region. The right hand tail may even extend beyond the upper critical value. In sketch D the curve has moved back to a mean of 8 and we are back to TYPE I error possibilities. Sketches E and F are simple mirror images of C and B as the lower tail moves past the acceptance region.

Electrons do not 'hang' around on their own in an electrolyte. An electrolyte is a solution, gel or paste, containing ions and a solvent or a bulking material such as a gel. Overall the electrolyte is neither positive nor negative it is neutral. Atoms or molecules become ions by either gaining or loosing one or more electrons from other atoms or molecules. Electrons themselves are far too reactive to hang around in the electrolyte on their own. They are always attached to some molecule or ion. Since electrons carry a negative charge, molecules that loose electrons become positive ions and those that gain electrons negative ions. When molecules form ions some reasily form positive ones, some readily form negative ones. Protons are positive ions formed from hydrogen atoms. So it is natural to find them in an electrolyte, unlike electrons. Electrons, however, can travel in a conductor and that is the purpose of the external circuit (wires). Because the positive ions congregate on ones side of the cell and the negative ones on the the other side there is a net movement of electrons within the cell towards the negative side, carried by the ions. The negative region doesn't carry on getting more and more negative, however, because the electrons return via the external circuit, balancing things up. Does this help?

I'm just shutting down for the night, so look again when I have has a chance to post something.

Are you really saying you do not consider any other physical laws apply?

Remember that the general solution will not in general be eigenfunctions, these arise when you apply the boundary conditions. The quantum equivalent of my stretched string is the 'particle in a box'.

Whilst English has many words or parts of words that come from Greek, 'pre' and 'post' come from Latin.

I am guessing that English is not your first language, so perhaps you are unsure of the difference between 'pre' and 'post'. 'pre' means before and 'post' means after. You cannot pretension a roof (or anything else) after it is in place, you post tension it. Apart from that, clamping the frame and ground together against seismic forces is an interesting idea.

Hi, Penelope, you haven't said what you field is (or I missed it) so it's difficult to offer specific thoughts. But hey, the world is your oyster, there are so many organisations, apart from straight academe, who would be glad to have you. If later in life you felt like returning there you could do so, some of my best lecturers at University had spent long stints in industry and some of the most unintelligible (though no doubt brilliant) had never been outside the classroom. California, huh, here are a few ideas Become a consultant to the film industry. Work for a dolphinarium Join Greenpeace .Join............

Yup that's what makes the world go round and be a better place. +1

I don't know this book. Has the text said anything about the acceptance criteria or decision rules or whatever? These are an indispensible part of hypothesis testing and your text in green doesn't seem to include them, so I don't see how you can come to any conclusion. As regards one tailed and two tailed tests, it is possible for only one tail of the two tailed test to fall within the considered area for typeII error comsideration.

I assume that you are observing that the terms random and infinity are abstract nouns, which have an existence in their own right, and inquiring if they possess a manifestation as a concrete noun in our material world? Since discussion has concentrated on infinity I will start with random. Sure I can point to a real worls example. Line up a dozen Cobalt 60 atoms and tell me in what order will they disintegrate. As for infinity, there are mathematical ways to handle the ratios of two infinities - it is called L'Hopital's rule and can be found on Google. However this is still abstract thinking. A concrete example is more difficult since we are limited by our own mortality or finiteness. So we are stuck with thought experiments which we could not carry out to the end at infinity. Would you accept the artists 'vanishing point' in perspective drawing as a real world example?

Mondie, you said you didn't want the algebra (you don't need calculus) to derive Bessel so I could only offer a worked example. You can replace my numbers by symbols and work out the squares ( the algebra is little more than expanding (a+b)2 for the general formulae.

This looks like the Greens Function solution by introducing the linear diffusion operator, L [math]L = \frac{\partial }{{\partial t}} - k{\nabla ^2}[/math] Have you considered the boundary conditions, both in time and space?

I did wonder if the clue lay in the word add pressure? This is what you do with partial pressures.

The ideal gas equation can be decomposed into Boyle's Law, Charles' Law and Avogadro's Law, although originally it was assembled as a composite from separate Laws. http://www.chemguide.co.uk/physical/kt/otherlaws.html Note the comment that this is not taught these days.

Thank you sensei, that's often what I do but I would not say I was in error, just that the parser (is that the right word?) was inadequate for the job, or that MathType (advertised on this site) was inadequate or both.

Judging from the comments I see on several forums many find the same problem I do. viz tex/mathjax/mathml, whatever, sometimes works and sometimes doesn't work for no reason apparent to the user. That is very frustrating after a substantial amount of typing work.

Many found Mathjax no improvement when PhysicsForums went to it. I wouldn't waste the time as it is no better.

Relative doesn't necessarily mean there is no absolute. It means that there is a connection between two quantities that can be expressed as an equation. This may be a subtraction, as with velocities and elevations above sea level. It may be a ratio (or division) as in my conker is five times as strong as nigel's new one. It may be a square root as in The increase in radius is the square root relative to the radius. and really any (mathematical) connection you can think of.