studiot

Sort of. We live in a three dimensional (of space) universe so I think the fruit cake analogy is better than the balloon one. Gauss's Law applies in all cases not just spheres and surfaces. The point of the fruit cake is that as the dough rises the cake expands in 3D. As it does so all the sultanas etc move further away from each other. So any interaction will take place of an increased distance.

As I understand what you are asking and rephrasing it The total energy in a given field, say electrostatic or magnetic, is being spread out over an increasing volume as the Universe expands. Does that not mean that the measures of field strength diminishes? The answer to this is yes it does. This is known as Gauss's Law. But matters are complicated because you have misunderstood some terminology. There is no such thing as 'potential force' There are various measures of field strength, appropriate to the particular type of field. These measure are also called flux density or field intensity. But you should not confuse this type of field with a quantum field, which is a different thing entirely. Also I think you should be careful not to confuse force and energy. These are different things that may exist independently. Finally potential is yet another different thing that I recommend you leave out until you have a proper handle on the others. So the first question is Which type of field do you wish to discuss?

I am having considerable trouble following what you think is happening and what you are taking into account. You say there is more water at the end in a vessel of constant volume? Where does this water come from? Clearly if there is more water, there is less polystyrene and you say you shorten the polystyrene strips. How? You say the volume remains constant. You also say the width and height remain constant. But you have marked none of these on your diagram so it is not clear what these dimensions refer to. Obviously to maintain these values constant the third dimension must change, can you indicate that as well? I don't see how you have calculated your energy values. Have you taken bouyancy into account?

Yes please I would like an answer to my polite straightforward question. Thank you moderator +1

Sorry, that won't wash as an explanation. Yes this bit is correct But There are several Zeno paradoxes. One of them is about an arrow. An arrow will never reach its target because Before it can cover the whole distance it must cover half that distance, leaving half the distance uncovered. No matter what speed it travels it there will always be half the distance remaining, however small. So it will never reach the target.

How does your hypothesis work with double blind testing, and why is double blind testing necessary if what you say is true?

Here is a picture that illustrates what I mean about the water movement and the wave. And here is a report on trials of a mechanical system alongside a harbour wall. It has many facts and figures about the size and frequency of waves and the power that can be extracted. https://www.sciencedirect.com/science/article/pii/S2092678215300480 And here are the salter ducks

There have been trials of arrays of distributed bobbing or nodding extractors, using wave action. But sea wave particles do not go up an down they go round and round. So a weighted shape, like a duck that bobs side to side is used. As swansont noted the frequency is low, perhaps 100 to 25 times lower than that of the ordianry mains. Also synchronisation of the array is not practicable both because the ducks drift about and because the wave itself passes irregularly. So for both these and storage reasons, the energy has to be converted perhps several times before final delivery. I will try to find some references when I have time

There are two types of 'things' in our universe. English calls them concrete nouns (such as brick) and abstract nouns (such as happiness). We do not know if any concrete things can or do go on forever (I have never heard of an infinite brick) - we do not even know if the whole universe is infinite or not. But all concrete things we know of (except perhaps the universe) of have a beginning and an end, which is how a brick is 9 inches long. But we have found abstract things that have a beginning (or they would not exist at all), but have no end The difference between 0.9 inches and 0.9 recurring is exactly this. And 9, 0.9 0.3 are abstract things. /Edit In respect of Zeno's paradoxes, The path and time are concrete things with start and finish lines so are finite. The division is an abstract thing which has a start but may have no finish, although obviously you can stop dividing at any point if you wish /Endedit Does this help?

In the derivation of a wave equation from Maxwell's 3rd and 4th equations [math]\nabla \times E = \frac{{ - \partial B}}{{\partial t}}[/math] [math]\nabla \times H = \frac{{\partial D}}{{\partial t}}[/math] Use is made of substition of the so called constitutive equations stating the properties of transmission media in general. [math]D = \varepsilon E[/math] [math]B = \mu H[/math] [math]J = \sigma E[/math] In the last of these sigma is zero, hence J is zero in free space, which affects the magnetic equation. Substituting these and doing some algebra leads to The electric wave equation. [math]\frac{{{\partial ^2}{E_x}}}{{\partial {z^2}}} = {\varepsilon _0}{\mu _0}\frac{{{\partial ^2}{E_x}}}{{\partial {t^2}}}[/math] The constant on the RHS is equal to the reciprocal of the wave speed, hence [math]{c^2} = \frac{1}{{{\varepsilon _0}{\mu _0}}}[/math] Now consider what would happen if [math]\varepsilon [/math] and [math]\mu [/math] became infinite. The solution of the equation would become undefined and not a wave. So for any wave that does exist these must be finite.

Agreed but instead of the word travels doesn't this sound better? You are still thinking of it as a classical wave that travels spreads away from the source. The point of a wave packet is that it doesn't spread. That is how it models a travelling particle. I thought the moving graphics on Wiki described this rather well. A travelling EM (classical) wave takes its field along with it as it goes. That is how it spreads. The quantum field always occupies all the space available to it. Perturbation is another word for excitation and one mathematical way of approaching this is perturbation theory. But like everything else about quantum theory it is hydra like - multiheaded so no single one of our methods covers it all.

Why not?

Clasically yes indeed. Wiki is good on this. https://en.wikipedia.org/wiki/Impedance_of_free_space I think the finiteness comes form the fact that in the classical wave equation we are equating a function of space to a function of time (as a second order differential equation) and we would not have a wave if the constants were not finite. Note that the correct term for the excitation of the field representation is a wave packet not a wave. Again Wiki has a good picture. https://en.wikipedia.org/wiki/Wave_packet

Thank you. You obviously know a lot of shipyard types. (No doubt the salt of the earth and all that) But you also know a lot of good high level Physics. Do you never find non scientists using speed when they mean velocity or velocity when they mean speed, or mixing force and energy or power? water movement is even more general and covers even more cases, so what. Science needs to be specific so we can all agree what we are talking about.

Would you like to elaborate in this, perhaps with a simple worked example? In particular I am interested in this part of the statement What exactly do you mean by it and how does it fit with the idea that the wavelength = distance between adjacent wavefronts?

Like I said, the correct term is tidal stream and you will find them on Admiralty Charts, the Admiralty Tidal Stream Atlas and the Admiralty Manual of Tides. https://www.admiralty.co.uk/publications/miscellaneous-tidal-publications/admiralty-tidal-stream-atlases Since the Admiralty did almost all the work, mostly in the 19th century, they are entitled to set the terminology. But as a more pragmatic justification for differentiating between currents and tides. The tidal horizontal movement of water is the result of the vertical movement of the water surface as the rotation of the Moon moves it above the surface, its gravity causing a moving local 'hump'. Note that the gravitational interaction between the Earth and Moon means that the hump is not directly below the Moon. Water is drawn in from all directions to service this hump. So you cannot say the water is moving in a particular direction in quite the same way as a thermally or concentraction (salinity) driven current, which does not in any case lift the surface of the water.

Flutes and recorders act as open pipes. Reeded instruments like the clarinet act as closed pipes. A pipe has a node at a closed end and an antinode at an open one. https://www.google.co.uk/search?source=hp&ei=GinnWoSGNYakwAL816mgCg&q=is+a+flute+open+or+closed+at+the+end&oq=is+a+flute+open+or+closed+at+the+end&gs_l=psy-ab.3..33i22i29i30k1l5.1682.8680.0.9153.36.35.0.1.1.0.124.3295.24j11.35.0....0...1c.1.64.psy-ab..0.34.3130...0j46j0i131k1j0i46k1j0i131i46k1j46i131k1j0i3k1j0i10k1j0i22i30k1.0.Hg4WwcekEgc

You will be telling me that there are both direct and alternating ocean currents next. If you look on an Admiralty chart you will find the tidal streams marked. Tidals treams are the correct hydrographic term for the horizontal ( component of the) movement of water as a result of tidal action. Currents would exist, even if you took away the Moon and thus the tides and even if you took away the Earth's rotation. In fact that is a good place to start considering the movement of terrestrial waters.

+1 Nah, not a phantom. It mustha bin a Sassenach.

Perhaps your difficulty is in failing to distinguish between Mathematics and Physics. No thing in the physical world is quite a different concept from zero in Mathematics. Numbers and equations are in the province of Mathematics, which deals in mathematical objects as precisely defined as we can make them. Zero is such an object and therefore can be said to exist mathematically. The mathematical object 'zero' follows certain rules (yes Peano's are as good as any) which require 1*0 = 0*1 = 0

Well on the subject of a failure investigation here are the four areas that I would investigate. (one more than usual due to the construction technique). 1) Inadequate design. 2) Inadequate materials. 3) Inadequate Workmanship. 4) Misadventure during construction. As to calculations, I was simply looking for some dimensions, without which calculation cannot proceed. That was too much to ask huh? Despite the rules of this forum, I must wade through a 110 page doc? Thus I have been using your calculated forces. As such it is clear to me that even without any reinforcement at all the concrete of M11 was capable of surviving the maximum load you calculated. However you calculated a fancy spreadsheet that omitted two vital pieces of information. Firstly no mention of the links was made. These are provided to prevent bursting, which is the normal mode of compressive failure of short compressive members. The links also aid construction. Secondly no mention of length was made. This is required to determine the actual amount of reinforcement necessary to prevent bending and to satisfy the codes. But you have put in a lot of work and somewhere in those drawings I saw a note about the "shear failure at the connection". I have already queried the possibility of shear failure, and no connection details have been provided. But the big question is torsion. I note the form of the bridge is an inverted T. As such imbalanced loads (perhaps due to failue area 4) would introduce significant torsion in the members, which may not have been allowed for in the detailing. As I'm sure you are aware, the combination of torsional effects with shear and bending stress can be many times that of direct stresses from normal (=standard) loading.

This is still avoiding the point I made / question I asked which was How is it possible for a particle to change its energy if no force acts on it?

Torsion is the effect produced by two opposing (but separated) couples. A single couple will produce rotation. This similar to two opposing (but separated) forces combining to produce a couple.

At molecular level there is something called a screw dislocation in materials science theory. https://www.google.com/search?q=screw+dislocation&ie=utf-8&oe=utf-8&client=firefox-b At a larger scale it is responsible for the ocean gyres, due to the Coriolis force. Yes, this is a plastic behaviour and is used in soil mechanics to determine what is known as the Atterberg limits. https://www.google.com/search?client=firefox-b&ei=2GDkWqXwOcmZgAbE7LSAAw&q=atterberg+test&oq=atterberg+&gs_l=psy-ab.1.0.0l10.85674.87388.0.90364.10.10.0.0.0.0.178.1110.0j8.8.0.foo%2Ckpnr%3D200%2Ccfro%3D1.3..0...1.1.64.psy-ab..2.8.1102...0i67k1j0i131k1j0i131i46k1j46i131k1j0i10k1.0.l92DHmCneDg The simplest form is rolling a plastic material like dough or soil or plasticine between the fingers. Yes indeed torsion can be very destructive. This is often because very high stresses can be developed when it is combined with other forms of stress, which direct, shear and bending. I am going to be proposing this as a possible reason for the recent Florida Bridge collapse in the current thread on that subject here.

So are you now saying that you didn't mean this claim you made, so big and bold? Are you , in fact, now saying these are not the actual forces involved? For example a post tensioning force is not applied 'factored' . You jack until the required force is physically as measured. Incidentally ,code minimum steel is 0.4% here, if the Florida state code is anything like ours, and up to a maximum of 6%. So unless substantially greater loads than 1927 KIP were applied M11 was not technically under-reinforced.