studiot

Thank you for this response, which indeed contains much truth. But there is also much missing from that analysis. Further most of the comments in my post regard your discussion in this thread and you have not addressed these at all.

Could that be because you are not replying to my post ?

I can see that density and specific gravity are different concepts that are sometimes inappropriately substituted for each other. Often this substitution is unimportant, sometimes it matters. But what I can't see is why either were originally introduced into a thread about global warming. Further there is a difference between the density of an object and the density of a substance, and also between the specific gravity of an object and the S.G. of a substance. Then there is the problem of mass. It is not necessary to measure mechanical inertia to measure mass. (or density or S.G.) Nor is it necessary to measure mass to measure S.G.

I would be interested to hear you describe this 'stream' To me a stream implies different properties than a wave. (Huygen's Principle)

Excellent. I'm sorry my post was so stuffy and 'theoretical'. The rest is much more practical. Now I mentioned 'circuit elements' These are ideal black boxes - ideal in that they 'do what you want but you don't have to know how or why'. The element or box has one, two, three or four or sometimes many 'terminals' with which it interacts with the rest of the circuit elements via the nodes. One terminal is special - I only know of one example we call ground or earth. Two terminals are simple so let us take one of those. Say we connect one terminal to node A and the other to node B. Ohm's Law tells us that the current though this element is given by the product of a coefficient (called the conductance) and the voltage difference between nodes A and B. Of course the conductance is the reciprocal of the resistance for direct current or the reciprocal of the impedance for alternating current. (note the voltage difference between A and B may or may not be changing as a result). Other two terminal elements are voltage sources and current sources. Three terminal circuit elements allow three nodes to be accessed - examples are transistors thyristors etc. Elements called 'Four terminal networks' are really the bee's knees. Nearly every circuit element your could think of can be modelled by a four terminal network - transformers, motors, radio antenna, amplifiers, transducers and interestingly two, and three terminal networks (elements) I don't know where you are at in your EE studies - some of this you may have heard of, some not so ask if I am introducing stuff you haven't met before.

So the electrical engineering model it is. The engineering model is designed and intended to make things (electical equipment in this case) work. Engineers only delve into the finer points as far as they have to. So the model is based on two physical quantities, current and voltage. Other physical quantities such as conductor length are normally considered immaterial. The two quantities are further split up into currents and voltages in different parts of the equipment (called circuits) and the external effects on the environment (called loads or inputs or outputs). Sufficient (simultaneous) equations introduced to fully calculate conditions in the circuits, though short cuts are often availble if a full solutuon is not rquired. The circuit is represented by a collection of points (called nodes) at which the voltages are calculated and links or paths between the nodes through which the current flows; with each path having 'circuit elements' offering specific properties. These properties are stated in terms of coefficients applied to the currents passing through the link and the voltages appearing between specific nodes so that the already mentioned equations can be stated. Now the thing is that it does not matter to electrical circuit theory what a current is made of or how it works, it just matters that the currents and voltages follow the model or idealisation. And, of course the currents may be direct or alternating or transient (your pulse you asked about). In alternating current there is of course no positive or negative in the same way as with direct current. How are we getting on ?

What sort of electromagnetic waves are you describing, there are many different sorts, some of which are still under investigation. ? Have you heard of pilot waves, non linear waves, self resonant cavities, soliton waves.....................? This is neither completely true nor anything to do with the offered topic. I remember my physics teacher demonstrating resonance with his handkerchief to show how a discrete mechanical phenomenon can generate a periodic mechanical motion. Similar mechanisms are exploited in radio etc. Again doesn't this depend upon your model of electromagnetic waves ? And also on you model of quantum wave mechanics ? Nobel prize winner Wilczek champions this hypothesis, but has yet to achieve breakthrough.

What is to happen when the batteries wear out ? https://www.bbc.co.uk/news/business-56574779

First question, If you are studying electrical engineering, why post in Physics, not Engineering ? The short answer to your question is that negative charges do not 'travel to or accumulate around the negative terminal' in either the Engineering model or the Physics/Chemistry model of the physical processes that are going on. I wonder why the book said a non-zero resistance ? The smaller the resistance the bigger the energy pulse! And zero resistance (an engineering short circuit) will result in a flash and some melted metal. Please confirm which model you want to work on, they are quite different and meant for different purposes.

Compare the following Andesite Diorite Granidiorite Quartzite Granite (Pink) Rhyolite

Is this a school project ? Exchemist is quite right to look at gluing characteristics as glues are affected by pH. +1 However to start at the beginning. Plant fibre is composed of two natural polymers. Cellulose and Lignin. Both are neutral pH substances. But the water, salts and resins in wood make the natural wood somewhat acid. As the wood is seasoned it dries and the pH becomes less acid. But the natural acidity can return if the moisture in the wood increases again. On effect of the acidity is that nails etc will rust in wood. That is enough to be going on with until you describe your project and what you have found out for yourself.

I do hope that no teacher of Physics, Mechanics or Engineering Science would ever show such a diagram to the class, whatever the angle of the ramp. Understanding of Forces means understanding where to properly place them on diagrams.

Back on topic, I have had 5 fridges so far in my adult life. If I only ever had one and imagine this saving multiplied by the population and multiplied again by all the other 'throwaway' gadgets.......... Fridges in particular are a special point sinceeaach one contributes refrigerant to the envoronment. Article from this month's SAGA magazine. Enjoy the pun!

Nothing nonsensical about your question - many people have asked it over the centuries. I don't think this is a speculation, however. It is a straightforward mathematical question that deserves a straightforward mathematical answer, that you algebra book, despite its 600+ pages (Wow) probably doesn't offer you. The very short answer is yes it does, but you need to know a little bit of electrical engineering. In AC power engineering there are two quantities known as the real and apparent power in a circuit. Put simply the real power is the power measured on a true RMS power meter and is the power an electric fire would draw from the mains. It is calculated without using complex numbers. Most other electrical devices draw (ie those with motors, flourescent tubes, transformers etc) draw what is known as apparent power which uses complex arithmetic to calculate the values. This is not an inefficiency of these devices it is inherent in their mode of operation. It should be noted that there is a difference between imaginary numbers and complex numbers - they are not the same and do not follow quite the same algebraic rules. i is an imaginary number, not a complex number. The term complex derives from the fact that it is in two parts, unlike the real numbers (and the imaginary ones) which have only a single part or are simplex numbers. All complex numbers have a real part and an imaginary part so are a combination of two parts. Complex numbers are written in the form (a + ib) (They also have other formats) which clearly demonstrates this 'a' is the real part and 'ib' the imaginary part and the + sign denotes the combination of the two. But there are also 'complex' number systems that are composed of two real parts for example (a + √3b) called surds or extended real numbers. In this case no imaginary parts are involved.

OK thanks and my apologies. Reading more carefully I see that you did in fact say grade 9 not year 9. So the real lesson there is to always read the instruction (question) properly. As regards to what you should study. In Maths I would suggest making sure you are good at manipulating equations so that you can solve single equations and simultaneous equations. They will appear again and again in both Maths and Physics. In Physics I would recommend concentrating on the ideas rather than the detail at this stage. Pay particular attention to mechanics as most of the rest of Physics is presented in terms of the ideas of mechanics. So make sure you know what a force is and the difference betwen a force and pressure. If you have any particular questions just ask.

How can the concentration be dominant ? The value of K is only one of several (simultaneous) equations that a chemical reaction must satisfy. So to take the case of in the case of A + C = D , K = [D]/[A][C] again, what does the reaction equation say ? The reaction equation ( A + C = D) says that for every molecule or gram-mole of D created two molecules or gram moles (one of A and one of C) are removed when the reaction reaches equilibrium. But we do not have to start in equilibrium (or there would be no reaction). So we could start with quite different concentrations of A and C, say 1M for A and 0.1M for C. Initially we have [A] = 1.0 ; [C] = 0.1; [D] = 0 so the total quantity of reactantants = 1.1 mole/L and of products = 0 mole/L In that case the reaction could not reduce the concentration of A below (1.0 -0.1) = 0.9 mole/L because at that point it would run out of C. At that point we would have [A] = 0.9 ; [C] = 0; [D] = 0.1 So now we have a total of 0.9 mole/L of reactants and 0.1 mole/L of products, making a grand total of 1.0 mole/L ie a reduction. Perhaps you would like to consider the implications of what happens if K is 0.9,, 1.0 and 1.1 respectively ?

Good question, keep them coming. +1 First it is worth noting that rocks in general are not molten at the depths concerned and that rocks are made of minerals which are ionic crystals when solid. When these rocks melt they are called magmas. They melt for two reasons, heat and pressure release. Heat is generated as rocks are drawn downwards from above (subduction) or simply buried by earth movements and also rises from yet deeper layers. This rising heat is not evenly distributed but concentrates in vertical convection cells (plumes). However the deeper the rocks are the greater the pressure on them and so they cannot necessarily melt (turn into a liquid and flow) even if the temperature is above their melting point. The extra heat from below is one way to generate the molten state that is magma, and why volcanoes etc occur in some locations and not others. When such rock is moved upwards by earth movements the pressure is lowered or released and more rock melts to magma. When the melt occurs cations (+ve) and anions (-ve) are formed. Oxygen is often combined with elements such as silicon to form complex anions (SiO4)- which are stable at such temperatures and pressures. Water is also available and involved. Britannica has a good not too technical description. Note the opening statement. https://www.britannica.com/science/igneous-rock/Nature-of-magmas Does this help ?

That's even less clear. Say you have a reaction [math]A + C \leftrightarrow D[/math] or [math]A \leftrightarrow C + D[/math] What difference does the concentrations [A] ; [C] ; [D] make to K ? You haven't answered my question is this homework ?

Good advice from exchemist +1. One thing I am not clear about. What is year 9 in the Philipines ? Wikipedia says you talk of grade 9 not year 9 and there are some differences in different countries. So the UK year 9 is equivalent to the Us grade 8. Here is a useful converter table. https://www.pearsonclinical.co.uk/Sitedownloads/Miscpdfs/Gradetoage.pdf This is quite important as year 10 in the UK can be the year of the first important career exams.

Firstly welcome Zeusetc. Is this a homework question - it looks rather like one, except that you are not specific enough ? What do you mean by the concentration of the product (in the singular) and the concentration (again in the singular) of the reactants (in the plural ? Have you heard of addition or condensation reactions ?

It's not that simple and Bill has a point. It's just that The bending of light in variable density atmospheres by refraction was known a century and a half before 1973 and studied in connection with the anomalous astronomical readings as a proposed mechanism a century before 1973. Surveyors and Astronomers routinely use a correction to observations for refraction. Bill's problem is that refraction just doesn't produce the observed deflections. It was indeed the experimental readings from Principe and Sobral that matched the calculations of GR, when the refraction calculations didn't.

The Hill Sphere is not about or much to due to the shape of the body. It is the region of space around the body where gravity is controlled by that body. As such the region is subject to purturbation by other bodies, so the Moon purturbes the Hill Region (Hill was an astronmer) and the Earth purturbes the Sund's region etc. Within this region a smaller orbiting body will remain orbiting and not escape. It is said to be locked or gravitationally locked or tidally locked to the larger one. It may be noted that there is a small region round the Moon where the Moon has greater influence than the Earth and so a satellite could potentially orbit there.

No the Earth's Hill sphere is not spherical. Wikipedia has a good article on this, including excellent diagrams. https://en.wikipedia.org/wiki/Hill_sphere

Should a skilled orator like Hitler have been allowed free speech ? What about this lot ?

~A slippery slope to what ? The trouble with insisting on your rights/freedoms is that since people interact every such right/freedom affects the freedom/right of another person in some way. That is why rights/freedoms come with the caveat to use them responsibly. Aren't most members here glad that we have some arbiter - that hard worked person called a moderator - to stop further discussion on gibberish ? Edit Nice one Zap +1