studiot

Never mind.

~What function would you represent the 'halt' step by ?

In other places I like writing. and used to like here, something like " In post 53 you said xxxxxx either as a direct quote or in inverted commas." All you need, short and sweet, with no unnecessary encumberances. So problem 1 would not arise as the necessary material is included, and I have found that the above is also the easiest way to deal with problem 2. Another problem is quoting non textual material, either pictures or fomulae etc. Sometimes this doesn't work well.

Interesting questions. +1 We know that (some) gravitational waves passing through the solar system experience gravitational deflection and redshift in the same way that light does. So can we cause this ? I think we would need to grow alot to at least planetary size. Yes they can interfere with each other, but reflection I'm not so sure about since they are not obstructed by matter, unlike light. There are both linear and non linear models available.

There are two big problems with this approach. 1) Will other folks bother to click on the link to follow the discussion ? 2) Some posters seem to delight in exceedingly long posts perhaps also editing them whilst you are referring to them. Either way it the job is still not done with this method since if you want to ask a specific question about a specific line or comment you still have to quote that particular line. I also find that someone who wants to dissemble will answer the wrong line if you quote say two lines of a post or a two line post.

Thank you +1 This explains what someone else was trying to tell me, but I couldn't understand. But I hope you will agree that teh result is very cumbersome. I can't see many adopting it. So if I right click on the aforesaid text and paste the result into notepad I get for the enxt post in this thread ttps://www.scienceforums.net/topic/128812-numbering-posts/?do=findComment&comment=1230073 compared with your post ttps://www.scienceforums.net/topic/128812-numbering-posts/?do=findComment&comment=1230071 Which means that the numbering may be consecutive for the whole forum and fun for those that want to play around with programming, but is not consecutive for the thread. I like the speedo on my car to simply display speed not a calculation and routine I must perform. Not for my it isn't easier to make a list of references and lots of pretty boxes will clutter up the reply.

Great stuff. Yes, agreed, but over or around please. Agreed. So the question you asked before of where does the energy arise for it to leave does not arise. It always has the energy it arrives with. That of course implies the the wind never actually stops ie V is never actually zero. So my full on jet is really an absolute upper bound, which is why I said it was a very simplistic safe option. OK, this is the start of a form of analysis. If the rate of change of momentum has a value other than zero it implies a force is acting on something. So what do you think is applying a force to what please ?

Difficult to answer without knowing where you are or what your level of maths is. Note that some 'modern physics' books assume you know classical physics quite well so are best avoided unless you have this grounding. Some deserve the title/description Physics for the Modern World instead. I will only mention this type. Some good american authors are Arthur Beiser He has written several versions - try for Concepts of Modern Physics. Robert Mills An introduction to Contemporary Physics Exactly what it says on the tin. An introduction with lots of background explanation/ information. Mills has an exceptionally clear way with words. Leonard Susskind and Art Friedman Offer a three volume set in Penguin with the aim of 'The minimum you need to know for the subject@ Quite a bit harder than the first two. You need better maths for these. UK authors You will never go wrong with almost any edition of Nelkon and Parker Ordinary level Physics Advance level Physics If you will be looking at UK stuff you might also like to look at 'Engineering Science'. UK use to offer more practical, less mathematical, and wider aspect courses in what amounted to a combination of basic Physics and Materials Science, much of which has been dropped from 'modern physics' courses. They offer a quck and easy way to get many essential facts quickly.

The beauty of English is that you can build complex ideas and variations on them by creating phrases or a series of phrases, using modifying words. For example Field Number field Algebraic number field and so on

For a few years after I joined this forum had post numbering, and I for one was very pleased with the facility. When the system was transferred to new replacement software we lost that facility and when I enquired the administrators said that post numbering was not availbale in the new software. So if it can be done I would welcome it back with open arms. +1

Yes, you are correct. There were several versions of the caloric theory over time, Which is why I said "dates are all important". What someone may have though at one time could well have been quite different from what they thought 2o or 30 years lalter. Here is a short history of Caloric and what went before and to some extent after with dates https://en.wikipedia.org/wiki/Caloric_theory

Then you shouldn't make claims you have no knowlege of and can't or won't back up. You most definitely made claims about others than Carnot, naming several prominent workers from the past. Need I go on to find more or even mention that dreaded word Stirling ? You made these claims and I am asking for the third time for your references. As a reference point and example Thompson is recorded as being the first to ues the term internal energy in 1852.

Note again you have avoided a direct question. (That's the line with a question mark that you quoted). As I understand Carnot's crowning glory it was the realisation that "If you have a source of heat you can obtain work from it " or words to that effect. So please provide a proper reference with all important dates, as I requested.

I stand corrected. Thanks. +1

And who, exactly, realised that and when did this Eureka moment arrive ? You have been noted as castigating Carnot many times for his 'belief in caloric'

So rather than leave this thread on a sour note, I think I will post more of my thoughts on the actual subject. Firstly the stubborn factor of 1/2. I don't know why the code writes incorporated it but I do know thet acknowledge that the real wind velocity variest from near zero close to the ground to a maximum near the top of a wall. So taking the max velocity and multiplying it by some factor less than one seems reasonable as an average. The code also describes finding and using the centre of pressure for the actual application of teh wind load to the wall. Now a couple of other members have pointed out Newton's third law say that If the wind applies a force F to the wall then the wall applies an equal but opposite force F to the wind. So where does that leave my analysis ? Over cautious, but safe in engineering terms. Modern codes also stress that they are starting point average simple solutions with no complicating factors. And that the individual situations should take account of special circumstances, using wind tunnels if necessary. What lessons does that leave us with ? Well the wind stream is taken as steady and continuous. This poses difficulties for the idea that a region of higher density builds up near the wall as this cannot continue indefinitely. Eventually as much air must be leaving the vicinity as arrives. So what we can say is the the presence of the wall alters the stream pattern which is best represented as a pressure averaged over the whole face of the wall. This pressure is then converted to a representative force, applied at a suitable point. This point of application is important because Rocks wondered how the wind could blow over a wall. For a wall this collected force applies a moment about the wall foundation. As the wind changes this can cause rocking or oscillation. Such motion can cause the wall to shift over time on its foundation sometimes sufficiently to become unstable.

I'm suprised Tom didn't go back to the realy father of thermodynamics, that ancient Greek who thought the Earth was flat and that there were four elements earth, water, air and heat (fire). So can I quote them to promote my flat earth leanings ? Anyway going back to retrieve quotes from Carnot an his contemporaries it is not suprising the they talekd of 'destroying' heat. After all they thought it to be a substance. And their word for it was caloric, which unfortunately survives to this day in French as Chauler, Portugese and Spanish as calor, etc. Atom was another ancient Greek concept that we now understand quite differently from the original. So what, our knowlesdge and understanding of physics has improved over the millenia so keeping older ideas is only useful if for engineers if it provides an easy route to calculation or to historians.

Nah, it's the air-fuel mixture. Nothing would happen without that. And a lot of work is done on that mixture to raise its temperature, in part of the cycle.

well said. +1 @NTuft Cowan has a very easy transition from Newton to Eulerian to Lagrangian mechanics. Hamill is much more red loodedas the whole book is as its title suggests. But still relatively easy going.

Exactly. and what do you think the working fluid is in a diesel engine ?

Yes I see it at the end of the address bar. But how would my browser know which post I was looking at ? For instance it shows blah-blah-blah/6/#comment-1229858 for every post on page 6.

Very clear thank you. Clear that you have classed all combustion engines as not being heat engines.

All I see is a yellow (ish) box with a date and time popping up. But if you really have found a numbering system that would be marvelous.

Not necessarily. Some chemical reactions evolve or accept either work or heat or both sometimes with a temperature change, sometimes not. You made no answer to my previous post so this is the last time I attempt to help you.

Yes, a groups is simpler and more basic than a field. If you can demonstrate the set elements forming a group, your propsed field can inherit group properties to satisfy field axioms. Field, group, algebra are some of the many words that combine with others into specialist phrases. Here are some useful definitions for you in algebra and number theory.