studiot

Rotation and translation are separate transformations. There is no rotation that produces a pure translation and no trnaslation that produces a pure rotation.

You would likely find many more of these on the beach at the base of a basaltic cliff. The white veins are quartz that have permeated the basic fine grained black rock after it was formed, but before pieces broke off to form the beach pebbles. The shape will have resulted from water action 'tumbling' pieces eg on a pebble beach. Cornwall is a good place to look for such pebbles. A scale is a good idea to add to a photo such as yours.

Hi Danijel, You are right - this may underlie your difficulties in the Zeeman thread. Separating energy into 'Field Energy' and 'Potential Energy' is the difficult way to go about things. Choosing electric or magnetic fields makes it even more difficult since you have polarity to consider. There is only one polarity in gravity, for instance. For a full accounting, you also need to take consider what creates the field. Very often we ignore this, as for instance when considering the PE of a (much) smaller body in relation to the Earth. We attribute the PE to the small body, when in reality it belongs to the Earth -small body system. By far the best introductory explanation of all this that I know appears in Sears and Zemansky - University Physics, in the chapter entitled Work and Energy. Sears introduces Work, energy, the so called Work - Energy Theorem, conservation of energy, (system) internal work and internal energy and external work and external energy etc. The Work - Energy Theorem is the basis for the correct version of the equations you are trying out here. Here are two scans from the chapter. If you find these interesting there are 13 in all and a PM letting me have an Email that can receive jpegs would get you the rest. Once you have this chapter under your belt we can make more sense in your Zeeman/magnetic thread.

I see you have just joined so welcome. I am sorry to warn you that you have just wasted your first post as there is insufficient content for others to know what to discuss. Are you asking a question or making a statement? As a newcomer you should take note that links/videos are not enough and that you only have 5 posts available in the first 24 hours. So if you want this discussion thread to come to anything please think carefully before replying.

This BBC article examines work from around the world measuring Covid mutations. Sadly there are now viable mutations. https://www.bbc.co.uk/news/health-53325771

As you have example 3 shown the sequence is N C H C , whichever way round round work. But shouldn't the H be pointing backwards (the lowest priority), not sideways ?

Coincidentally there was an article on the artificial slowing of aging on today's news. https://www.ed.ac.uk/news/2020/blood-iron-levels-could-be-key-to-slowing-ageing

Not quite sure about your statement of the integral. What are you doing about x (a varaible) in the integral of f(x, y) dy ? Is this perhaps an attempt at the REgularity Theorem in the Calculus of Variations ? See page 112 here https://www.math.uni-leipzig.de/~miersemann/variabook.pdf

So does the amp control the speed of the motor? One way to do this is to configure a power amp in a bridge (or other) variable oscillator circuit. Varying the frequency of the supply to the motor varies the speed of the motor without loss of power.

What is there to do ? The subject has passed from pure science into engineering and been forgotten. I have at least (older) three textbooks dedicated to the subject of what happens to electrons in a vacuum in a whole variety of circumstances.

So why is the substance to be liquid at a lower temperature than when it is a solid ?

Would you like to reconsider this question or explain what you mean ?

I'm afraid I'm not knowledgable about the manufacture of silicon products or why you would need such a power amp for the purpose. At that power is it a class D or switching amp of some sort? At 750 watts output (genuine RMS measure ? ) the switching frequencies and noise generation will be within the range of the scope. Divide by 10 probes are used as the division also reduces the input capacitance of the measuring system by this factor. Such reduction becomes more and more important the higher the frequency as it reduces signal distortion. A competent electronics tech should understand this.

This is a very old scope, designed for TV / Radio repair shops repairing analog TV, radio and audio equipment, digital clocks etc. What are you going to use it for ? If you do not already know how to use it here is a Hitachi operation manual pdf https://mpe.berklee.edu/documents/studio/manuals/testingmet/Hitachi V212/V-211 V-212 Operation Manual.pdf This decribes the correct use of the probes on page 17. The probes appear to be fixed division (divide by10) capacitive input, so they will not be suitable for DC signals, or very slowly varying ones. At x10 and x 1 probe will have a switch to divide by the signal by 1 or by 10. The x means divide by not multiply by. So you have to multiply by the same factor to get the true reading.

So what was it you wanted explained?

Thank you for those useful points, joigus +1

This EU report may interest you. It is 2010, but I don't think there is a more recent one. https://ec.europa.eu/environment/ecolabel/documents/Laundry Detergents technical report.pdf

I agree we have yet to discover the perfect universal material, and probably never will. Some things I would add to your list of good and bad. The pvc wiring covering is basically hard brittle plastic. So a plasticiser was added to make the material softer and flexible. But in time this plasticiser evaporates out, leaving the hardened pvc. There are also aesthetic / comfort requirements that lead to many early uses of plastic being abandoned. For example static and the nylon shirt.

I am sorry I did not ( and still don't) have time for diagrams in my last post. Repository was used deliberately as available energy because the energy is distributed or partitioned between different degrees of freedom. The potential energy of a magnetic dipole in a field is the (angular) work done to align it with the field. Some diagrams will help and I hope to post them tomorrow. Meanwhile I am not sure what your interest in this is. The Zeeman effect is spectroscopic and only occurs for energy transitions. The splitting of energy states due to immersion in a magnetic field happens anyway and does not require and energy transition. It is just shown up by the Zeeman effect. All will become clear with some diagrams.

I recommend you ditch that model and its source pronto. What is says is only incorrect in a very subtle point, but is is woefully incomplete. It is incorrect because molecules do not feel pressure. They are just not big enough. Pressure is a macroscopic phenomenon on fluid 'particles' or fluid elements, which are much bigger than molecules. So taking those balls as fluid elements they experience pressure as shown including the missing 'reaction' from he bottom of the container in the second diagram. I can just see the tops of the hidden arrows under the bottom rows of balls. However pressure is isotropic which means that at any point in the fluid it is the same in all directions. Pressure is a scalar not a vector. So the diagram should have included horizontal force vectors and reaction vectors from the sidewalls and the underside of the 'toe' in the second diagram. (This last reaction answers your question) Also the fluid elements would have been better drawn as little bricks or cubes. Balls leave spaces between the points where they touch, but there are no spaces in fluids. I will take this opportunity to off a tip , which is what I thought the thread was going to be about when I read the title. There are often several forces active but one may be so dominant that others can be ignored. This is true of molecules in fluids. They do not feel the pressure force, but they are susceptible to surface forces, including surface tension. Chemically and Biologically this has great significance for life, chemical reactions, cells and so on. In Physics the balance of presssure, surface and gravitational forces determine the type and transmission of waves. Similarly we ignore gravitational forces in the atom, which are many orders of magnitude weaker than the electrostatic ones. Yet the electrostatic ones are outmatched by the strong nuclear force at very short range.

This is a genuine sub sub branch of Pure Mathematics which is very obscure. Try reading this Wikipedia has a simple offering for once https://en.wikipedia.org/wiki/Limited_principle_of_omniscience Then read a full blooded paper from Birmingham University https://www.cs.bham.ac.uk/~mhe/papers/omniscient-journal-revised.pdf Avoid the religious books by Paul Tranter They are not connected. https://books.google.co.uk/books?id=I8bKDwAAQBAJ&pg=PA69&source=gbs_selected_pages&cad=2#v=onepage&q&f=false

Preparations vary in their disinfectant capabilities. Contact time is also an important factor. Alcohols are substantially less effective viricidal agents than bactericidal. Many studies have been conducted. Here is a good reliable summary one from Stanford & Virginia Universities. https://ehs.stanford.edu/reference/comparing-different-disinfectants

This question that shows some good thinking. +1 Since the answer can be quite complicated I will try to start with a simple version. You have asked about orbitals, which are of quantum theory origin. But your consideration is from classical theory. So let's sort that out first. There are two types of energy repository involved with the interaction of electrons (in atoms) and magnetic fields. The first can be answered satisfactorily and results in what is called the normal Zeeman effect. Classically the electron (mass,m) orbits the nucleus at a particular radius, r, with velocity vo due to electric forces between the electron and the nucleus. So the electron is moving under the action of a central force Fo, so by Newton's second law [math]{F_0} = \frac{{mv_0^2}}{r} = m\omega _0^2r[/math] where vo is the linear tangential velocity of the electron and wo is the angular velocity due to the circular motion. If a suitable magnetic field is now applied (that is perpendicular to the plane of the orbit) two things will happen. During the time the magnetic field is being established there will be an electric field tangent to the orbit because of the emf generated by the changing magnetic flux. At the same time there will be an additional force on the electron perpendicular to the magnetic field and to the velocity of the electron that is radial to the orbit and in its plane. This additional force can be inwards (towards the nucleus) or outwards, depending upon the direction the electron is travelling around its orbit. The additional force is also small compared to the electrostatic force which maintains the orbit radius r. So there is negligable change to the orbit radius, but the electron speeds up a little or slow down a little to adjust for the two new values of Fo, one slightly lower and one slightly higher. The derivation is quite simple and you can have it if you like, but the result is [math]v = {v_0} \pm \frac{{eH}}{{4\pi m}}[/math] So classically the energy repository is due to a change in the velocity of the electron not the shape (radius) of the orbit. Thus the ground energy state is split into two, one slightly higher and one slightly lower. The spectroscopic Zeeman effect is the result of transitions between energy states (usually the ground and another), each of which is split so the number of spectral line increases. But the story is not yet over since a second type of energy repository is available that is a quantum effect. This is due to the quantum spin of the electron and leads to an additional quantum number. Unlike the classical value above the quantum values can only come in discrete values.where the spin is aligned parallel or antiparallel to the magnetic field. Any questions?

I had hoped we had returned to more normal forms of discussion. Since that is not the case I will leave you with the suggestion. Get a good English (or better Thermodynamic) Dictionary and look up the words 'piston' , which Mandl did not use, and 'partition', which he did. Both word have very particular and carefully defined meanings. go well and enjoy your stay in the Netherlands - I find it a very nice place.

Before this degenerates into another slanging match, let me step in here. Seth, you are mixing up macroscopic mechanical theory and microscopic kinetic theory. This link is proper statistics, you cannot 'mix and match' formulae from macroscopic and microscopic theory without doing this. No one is suggesting that in Mandl's diagram the system passes directly from state a to state b or from state b to state a. Either way the change is a gradual process, although there is a vast different of timescale between a to b and b to a. Consider first b to a There must be a first molecule that leaves side A and moves into side b Followed by a second, third and so on, although sometimes and sometimes only , two or molecules will exit the gap simultaneously. So , however fast or slow, the system must leave state b a bit at a time and move, a bit at a time, towards state a. A similar deduction may be made for the reverse process a to b. Now statistically the more particles there are the harder or less likely it is for most (all) of them to move from one side to the other, at or near the same instant. Your centre of mass argument is also suspect My single particle example negates that as its COM is always moving, but by Newton's laws, zero work is being done. Finally I said that Mandl's example was presented in his introduction to the second law. Like all good courses and texts he is up front about the difficult cases, where the simple theory is insufficient, but I also said he treats this later.