studiot

You have 17 posts, you should be able to post an image, contact a moderator, they are very helpful. Are you doing it right? Make sure the image is not too large a file 800 x 600 pixels is a good size for the web and helps with the upload. 3.6M+ from a digital camera is overkill If need be, open the image in a graphics program such as paint and resize. Choose more reply options to the bottom right of the bottom post it box When the more reply options opens Clcik browse at the bottom When you have found the image select it and it's appears in the box, Click attach this file You can then click somewhere in you text for posting and click to the bottom right to insert it, otherwise it appears as a thumbnail at the bottom.

I see no diagram? I think it is also time to remind you of telephone regulations. The telephone system generally has around 50 volts on the ringer circuit. This can be dangerous, not only to humans but also to equipment. As a result it is illegal in most countries to play around like this with telephone connections. The purpose of the filter (splitter) is to remove the ADSL signal from the voice signal (not the other way round). So once you have split the signals the voice will continue on, but will no longer be carrying the ADSL signal. The ADSL signal will then be available at the alternative output, which quite deliberately has a different socket.

Wow !*! What have said to deserve such opprobrium? You made an absolute statement - no exceptions - you said yourself it was absolute. I will quote it again since you chose to exclude the context from my comments. Now tell me what the logic output of a 74C126 buffer can be? I will give you a hint; this a Tri State buffer electronics chip.

Rubbish. Statement: The grass is green. That statement is neither logical nor illogical. It may be true if I am standing in a field at noon in May, It may be false if I am standing in the same field at midnight, under a sodium street light.

I'm so sorry the moderators have failed so miserably on this occasion. sheep, you do realise that the main reason for closing your last thread was not to protect others from your offerings, but to protect you from others. By starting this current thread you have totally circumvented their aim. And furthermore mods, I wish to complain as I was forced to reduce the number of emoticons to what you see now. So they do not match the line length anywhere near so prettily.

I'm sorry I don't see this. Take an uninflated balloon. The skin is floppy since it is in neither tension nor compression. Now blow it up. The outward radial forces due to the pressure lead to tension in the skin. The balloon takes on a round shape, with radius and tension increasing with pressure. Now let some air out to reduce some pressure. This does not lead to compression, merely a reduction of tension. In fact you can reduce the pressure all the way back to zero without introducing compression. Now inflate the balloon again and then stick some plates to the outside surface of the balloon, so that there are gaps betweeen the plate edges. Again partially deflate the balloon to simulate mantle shrinking. The object will shrink and two plate edges will eventually touch. At this stage this introduces neither longitudinal tension nor compression into the plates. Further shrinking will introduce a reaction force between the two plate edges in contact, but this will only serve to nudge the two plates aside, it will not yet introduce internal longitudinal forces in the plates. Now reduce the pressure still further and eventually one of the plates will encounter a second plate edge. This still will not induce longitudinal forces as the other edge of the third plate is still free to move so can be pushed aside. Further pressure reduction will eventually lead to a complete ring of plates and at this point pressure reduction starts to induce longitudinal compression forces in the plate ring. The plates now have several possible actions or even a combination them. They can hinge, thrusting the junction of two plates outwards. They can squash. Overlap can occur. They they increase their curvature pushing outwards a section of plate between the plate junctions. This is presumably what you mean by arching. This simplistic picture is complicated by any shear forces between the surface of the ballon (mantle surface) and the plates.

Curved, yes. Arched, I would like to explore further. There is a big difference between arched and curved in my book. An arch is a purely compression structure that cannot support tension. Its unique claim to fame is that it transposes transverse loads to circumferential compression, so long as there is a compressive reaction at both ends. That is it rotates the line of action of the load through 90 degrees. If you have tension at one end of a plate due to an opening (a trench?) and compression at the other due to a closing how do you achieve arching action? I'm not saying it doesn't happen I'm saying you need to think this aspect through in more detail. In particular an arch has compression on the underside, whereas a beam has tension on the underside. If you are clever, or conditions are suitable, you can arrange for full or partial cancellation of one by the other.

You didn't understand. What do you measure x in? metres? miles? So what do you measure the change in x in? metres? miles? Why is that not a form of negative length?

HalfWit has given you (post#13) the mathematical definition and reason why a straightforward distance (length) cannot be negative (by definition). What I am asking you to consider is The difference between two distances (lengths) is still technically a distance (length), so can this be negative? That is what happens to (L2- L1) when L2 < L1 ?

Vectors are most definitely not what I am talking about. Expansion and contraction have 1D, 2D and 3D versions. Take a cube, heat it up, cool it down. It expands and contracts Where are the vectors? When it is smaller is the length of side, area or volume that no longer exists negative?

The extension of an unstretched or compressed spring is zero. So if I stretch a spring is the length of the extension positive or negative, given that the spring is now longer? If I compress the spring is the extension now positive or negative, given that the spring is now shorter?

Agreed useful polytropic formulae are [math]\frac{{{V_2}}}{{{V_1}}} = {\left( {\frac{{{P_1}}}{{{P_2}}}} \right)^{\frac{1}{n}}} = {\left( {\frac{{{T_1}}}{{{T_2}}}} \right)^{\frac{1}{{n - 1}}}}[/math] Note that the pressure and temp ratios are the other way up to the volume ratio. There are two versions of the First Law It looks as if you are using the physicists and engineers version [math]\Delta U = Q - W[/math] That is delta U = Heat added to the system minus work done by the system. Note that the first term on the right represents energy in and the second represents energy out. Chemists use the alternative [math]\Delta U = Q + W[/math] In which we consider all forms of energy in as positive in out as negative. For chemists delta U equals heat input to the sytem plus work done on the system.

Are you sure of your sign conventions and arithmetic? Does the negative sign mean heat is also added or evolved? ?

If you have genuinely calculated p2 from the polytropic law then that is the compressed pressure. Pressures are not additive, unless they are partial pressures for different gases. But why not tell us your calculation? That is the normal etiquette for homework help.

Hello, arc, would you like to explain this arch loading a bit further? Arching action in beams, plates and shells is well known and accounts for the increased strength of members in bending as comapred to simple theory. Further the arching action leads to a lower energy state for the loaded member.

But we already have a concept and definition of negative length. Work done = force times distance moved in the direction of that force. So distance in the opposite direction (ie against the force) is negative, as is the work. In mechanics, extension is reckoned positive, contraction negative.

With regard to your model, it is an interesting idea. You can certainly map an octant of 3D space to 3 orthogonal planes, formed as you have shown from folded paper. And as you say all points in each plane can be reached by a radius vector from the origin and 0< an angle <90, which makes 270 in all. This is similar to the process often used called normalisation for a graph or the formation of nomograms. The normalisation process uses the fact that there are as many points between 0 and 1 as there are between 0 and infinity. Note that your map only covers 1/8 of 3D space, although if you introduce signs you can cover 2/8. Since you like models have a look at Mathematical Models by Cundy and Rollet They show how to make some fascinating paper, string, rod, glass and other models in mechanics, geometry, non euclidian geometry (Mobius strips Klein bottles etc), tesselations, knots, fancy curves, fractals, logic and more fields of maths.

I don't think you quite meant that?

Does this include trancendentals ?

Yeah I aways get the short end of the stick.

I can tell you that between 0811 to 0817 GMT (London time) every morning SF is offline in my neck of the woods. If I have made my tea before 0811 then it starts and suddenly freezez at 0811 and comes back on after I've had breakfast at around 0840. On Wednesday this week it was offline for about one and a half hours at that time.

I think you are still pulling technical terms out of a hat, guessing at what you think or would like their accepted definition to be and then building your castle upon your own notions. Unfortunately that impedes communication with others. Why not simply use accepted definition of terms and if you introduce a new notion then use a new term? The most famous system of logic/maths in history is Euclid's 'Elements' It is based on 23 definitions, 5 axioms (he called them propositions) and 5 'common notions', all stated without proof. The very first definition is 1) A point is that which has no part. (This is taken to mean a point is indivisible into parts.) By definition 15 we find out that 15) A circle is a plane figure contained by one line such that all straight lines falling upon it from one point, among those lying within the figure, are equal to one and other. To recap. Numbers and points do not have dimensions. There are multiple definitions of the terms number, point and dimension already in use. If you wish to pursue your 3/4 idea perhaps you should compare with Mobius strips and Peano curves? They have allied interesting properties.

The only statement of yours that I have refuted is the claim you made several times (without proof or justification) that the circle does not exist in either mathematics or reality. I offered real world examples of the existence of a circles, as evidence for my statemnt that they do indeed exist in reality. If it does not exist in mathematics why do you say this In fact we are apparently agreed on a definition. Yes and I have pointed you several times at the fact this this notion of a circle, although different from the locus definition, has implementation in both mathematics and English. In English we talk of a circular walk, a circular argument etc In maths the idea is reflected in the topological notion of a closed loop So you are seeing an adversarial stance where none exists. However I think that talking in circles has taken this thread away from the original point which was about the relastionship between dimension and number. Talking about time (there is no need to shout) would diverge even further, which is why I have avoided it so far. I'm not actually sure whether time is an abstract or concrete noun, or falls somewhere in between in the 'unclassified' basket. In any event, you need to be careful slapping the word time against an axis and calling the result 4D. The forms of physics that create 4D spaces use ct for that axis to preserve compatibility with the other spatial axes.

I think you said that English is not your first language. Well it is certainly mine, so I recommend you take some notice and respond to points made about it. Not all languages have the concept of abstract and concrete nouns, so do you understand this? It is vitally important to an english word like circle which is an abstract noun.

Of course there is, both in maths and reality. Neither you, nor I, nor anyone else can redefine the circle in mathematics, which is what you are trying to do, and imatfaal has already commented on. Mathematically a circle is defined as a particular locus. In the real world we can actually trace out this locus, so the 'real' circle has real existence. It does not matter that there is not perfectly circular real world object. A (circular) cut through an object will do if you want a concrete noun. If you want abstract nouns then consider a range-range navigation system. The position lines of a rover in this system are perfectly circular. And yes the position line exist as much as other abstract nouns such as the colour red or the emotion joy.