studiot

Whilst I agree that selection and evolution can be connected I don't accept that this is always the case. They are separate distinct processes. Change over time is another thing again, which I think too large in scope. Usually the connection is that as small variation of an offspring of a member of a population leads to another slightly different member of that population. For example a smaller or larger elephant with a slightly longer or shorter trunk may have an evolutionary advantage, but is still an elephant. A dinosaur faced with the external event of the chixelub meteor underwent an entirely different change, although top of the then evolutionary tree.

Thanks. +1

We are all (well nearly all) learning things here. +1 Please note my comment about dialect and the pronunciation of the word bath. Also compare bath and bathilith.

So you are using this to preach that you know everything there is to know about these things instead of listening to see what others might know. ? I asked if you know the difference between a scalar and a vector to try to help you you understand what swnasont and I are both saying, but from different viewpoints. The positive and negative convention used in an electric field refers to the direction part of the electric field vector, it does not refer to the magnitude. Charge on the other hand does refer to the magnitude, since charge is a scalar and has no direction.

Would that not be artificial selection? I'm sorry I missed this reply. No it would not be artificial , nor would it be selection in the darwinian sense. I am suggestng the definition of the word evolution you are employing is too narrow to cover all possible/conceivable circumstances.

We all know that the Sun, the Earth, the Moon and the terrestrial waters are in motion. None is static. So static is the wrong word to use. We call what you mean by static theory the equilibrium theory and you are correct it was due to Newton, centuries ago. You are also correct that it is a very crude inadequate model, But is does correctly identify the forces involved as a combination of gravitational and rotational and that gravitational forces dominate the force part of the equation, but that rotational speeds dominate the timing part of the equation. A better theory, which also allows for the fact that the rotational axis of the Moon's orbit is not parallel to the Earth's own rotational axis and a few other effects is known as The dynamical theory of tides. But this is still based on Newton's force analysis. As I have shown your figure of 1600 km/hr is approcimately correct. But I have also shown that it does not correctly model the system as the timing of the moon's periodic function is not the same as the mechanical resonant frequencies of the water. Do you understand what this means ? The simplest method of approaching this is to model the hydrographic response as a fourier series rsonant with the lunar driving force, which introduces the humps you mention and use actual observations to calibrate the fourier coefficients to suit. A yet better mechanical model is to consider the lunar driving force as a 'Forcing Function' with a frequency near to the resonant to a non resonant system. Are you familiar with the maths of this ? It produces frequencies not in the oringinal lunar function nor the resonant response of the hydrographic system. So to echo swansont's words Why have you repeated your earlier posting ? What are you trying to achieve here ?

They used to add amyl meta cresol or hexachlorophene to toothpaste once upon a time, until it was banned. What is the form of this 'silica' it doesn't say. However I do take your point that it seems to be used in lots of other thing meant for ingestion.

It doesn't bother me, it was just an oddity that sometimes appears on my screen, like that business of the unidentified notification I reported and everyone tried to tell me was my doing until Capt'n sorted it out. I didn't think to get a screen capture last time it appeared, but I will do next time.

Do you understand the difference between a vector and a scalar ? You haven't responded to my statement about this.

Exactly. Personally I am uncomfortable with the idea that the stated grease is 10% 'silica' , an known carcinogen.

I just don't get your point.

I've not seen that analogy before, +1

I'm sorry, this is not a proper discussion. I am reading what you say, and addressing your points, a few of which I agree with a few I disagree with and some are just plain wrong by observation. You are simply writing longer and longer versions of the false assumptions without answering my questions about observations on reality. Another plain wrong statement would be If this is an answer to my comment about circuit theory then it is just plain wrong. The sign convention for charge (and current) is opposite to that of voltage (potential). Please answer the questions I have asked instead of ploughing on as if they had not been asked.

How is this any sort of answer to my points? In fact all you have done is reiterated my point about the difference between charge and current. A further question, to emphasis the point raised by swansont. Every day, throughout the universe, electrons are taking part in chemical reactions, many of which give of photons. Those atoms concerned along with their electrons, will go on to take part in more chemical reactions up to an enormous number. If each time this happens how come the charge on the electron does not diminish by the charges you claim now reside in the electric fied of the photons ? In other words how come the charge on all electrons is not decaying over time in the whole universe ? Or do you not accept the principle of conservation of charge ?

Not in the case of an EM field it doesn't. An electron in an atom can emit a photon in the ionisation process and then be destroyed by a subsequent nulcear reaction. Yet the photon will remain forever or until it is absorbed somewhere else, which ever comes sooner. What about answers to my questions ?

A very disappointing response to my polite and pertinent question. I have another pertinent observation/question. The assignation/term positive or negative refer to different properties for charge and electric fields. This is reflected in the fact, often missed, that in electric circuit theory (where we have current not charge) there are two (not one) sign conventions in play. As a mechanical engineer you should have a good understanding of sign conventions and their implications. Charge is a scalar. the electric field is constructed from vectors and the sign convention lies in the vector in the latter and the scalar in the former.

No I have never seen explicit reference to those invoked.

External intervention, deliberate or otherwise.

Two things about bots. This piece of business news Apparantly NYT allege that ChatGPT was trained on many writings that are their copyright and is now regurgitating them, without permission. and my own recent experience with Google. I have noticed that when googling a question especially a technical calculation, the top reference is sometimes to a ChatGPT reply and this gradually getting more frequent. I will post a screeshot next time I get an example

I am sorry to rain on your parade, but such theory already exists (and has done since Newton's forward and backward difference formulae) Iterative methods are also called recursive methods in Analysis and Calculus and come in two flavours : Linear and Non linear recursion. There are also iterated integrals (Fubinis Theorem) and iterated series.

Please note what it says on the website. https://www.google.co.uk/search?q=Btech+applied+science+unit+14A&sca_esv=594049696&source=hp&ei=eGqMZcbKCLnWhbIPrra4gAo&iflsig=AO6bgOgAAAAAZYx4iBjvsOtDmoB1KoM0zZkkk8SVAYP3&ved=0ahUKEwjG5t6cnbCDAxU5a0EAHS4bDqAQ4dUDCAw&uact=5&oq=Btech+applied+science+unit+14A&gs_lp=Egdnd3Mtd2l6Ih5CdGVjaCBhcHBsaWVkIHNjaWVuY2UgdW5pdCAxNEEyBxAhGKABGAoyBxAhGKABGApI10NQAFj6QHAAeACQAQCYAbYBoAGcGKoBBTE1LjE1uAEDyAEA-AEBwgIREC4YgAQYsQMYgwEYxwEY0QPCAhEQLhiABBiKBRixAxiDARjUAsICCxAAGIAEGLEDGIMBwgIOEC4YgAQYsQMYxwEY0QPCAggQABiABBixA8ICDRAAGIAEGLEDGIMBGArCAgoQABiABBixAxgKwgIFEAAYgATCAgsQLhiABBjHARivAcICBxAAGIAEGArCAg4QLhiABBjHARivARiOBcICBxAuGIAEGArCAgcQABiABBgNwgIIEAAYFhgeGArCAgYQABgWGB7CAgsQABiABBiKBRiGAw&sclient=gws-wiz#ip=1 This stuff is University level, definitely above A level, it was not even on my S level all those years ago. So you have have quite a few prerequisites in Chemistry before attempting it. As exchemist said you don't solve chemical equations they are nothing like mathematical ones. And they don't have terms they have species - reagents and products. In fact they are more like a recipe in cookery. Eggs + flour + water = egg noodles Eggs + flour + water = bread Should should we really be starting by finding out what the question you were asked really said, because it said nothing about solving ?

Show us that you have done some work on this before seeking help. Do you understand what the substances are, can you write formulae for any of them ?

I don't agree. So an electric field is generayed by a charged particle, say an electron. But once the field has left the electron what destroys it, or why can't it exist without the electron ? What in Maxwell's or other equations prevents this ?

I wonder if there is a language difficulty because you seem to be asking questions (which is good) rather than trying to preach. But I would say that you are posting too much at once. So I am going to start with the first part of your post and begin to answer these questions. Then we can see how we go. So the Moon orbits the Earthonce every 27.3 days which makes it angular speed of 2π / (27.3 x24) radians per hour. This is approximately 0.01 rads/hr.. (It will become clear why I am using these units) The Earth also rotates at an angular speed of 2π/24 radians per hour Which is approximately 0.26 rads/hr. Since both rotations are in the same direction the net rotational difference is their difference or 0.26 - 0.01 = 0.25 rads/hr. The radius of the Earth is 6731 kilometres. So if a static bulge is to keep up with the moon is must travel at 6731 x 0.25 km per hour. This agrees with your calculation. A wave travelling at this speed is the basis of the simple dynamic theory. But this theory is only applicable within the following constraints. If the depth of the water is d in km then waves of wavelength L will propagate witha velocity of v = √(gL/2π) for waves in deep water. Where g is the acceleration due to gravity in km/hr2 which is 127008 km/hr2 This makes the wavelength as (1600*1600*2π) / 127008 or 127 km. However this formulae is only valid for d/L greater than 0.5. Now the average depth of the ocean is around 3.6 km and tha max depth is only 11 km (NOAA) So dl << 0.5 and the condition is not satisfied for the deep water formulae. Which makes the ocean too shallow for a simple resonant system. So instead we must use the shallow water which then includes the effect of the bottom and other topography. The formula for such waves is given by v = √(gd) Which is good to around (1600 * 1600) /127008 km Which is approximately 20km. This emans that the wave equation is no longer homogenous (equal to zero in this case) There is now a forcing term involved as well and the theory is known as forcing. Does this help and do you wish to continue ?

If you are prepared to listen to the explanation and to follow it as it is developed bit by bit then I am happy to discuss your request with you. The above are very reasonable wish to explore in more detail the short statements you have already been offered. So we should start with 2 matters. Firstly the issue of 'work'. Do you know what 'work' is. Without a good understanding of this you will not understand the answer. Secondly I said there are several ways something can have energy so we should start with the simplest, which is also the easiest to relate to 'work'. The simplest type of energy is called Potential Energy and is the energy of configuration. For a simple system, for example when there are only two objects involved, the 'configuration' may be as simple as the distance between them. When that configuration changes the distance between them changes and the potential energy changes. That potential energy is equal to the work done in the change and how we get the statement Energy is the capacity to do work.