studiot

Just to clarify something for you. It is implied in what is being said about horizontal that posters are approximating the Earth (or Moon) to a flat surface in the region where the stone is being thrown sideways and that a horizontal line is a straight line at right angles to the vertical at the point of projection. Of course in reality the surface of the Earth etc is curved, not flat and a truly horizontal line is a curved line that follows this curve.

Actually I think there would be a difference as I said. Remember the OP only asked about the signs of positive and negative charge. This offset this change in our set of physics equations would mean changing the sign of the vector cross product. Such a change would preserve the electrical equations containing pseudovectors specific to electricity but not all cross product pseudovectors are to do with electricity. What about the outward normal to area or the torque pseudovector? Which way would they point if we did this?

A general balance of forces does not necessarily mean equilibrium. You need to complete your course in your Torque thread to find out more. If you must know, it is called Poinsot's Theorem.

A pretty good rendition from my Hymn sheet.

Where did this question come from, seems a bit odd to say that only one choice could not be the pH. I can see only one pH that matches all the indicators in the table, however, and it is not 7. What are your thoughts?

The eye-ring is a stop placed where the eyepiece forms an image of the objective. Its diameter is just sufficient to enclose all rays passing through the instrument. In a telescope the eye-piece comes just outside the eyepiece. The magnification or magnifying powere is the ratio of the objective diameter to the eye-ring diameter. The diameter of the eye-ring should not exceed that of the pupil of the eye.

This is a discussion forum and I made the point that physical objects are not points, they have physical sizes which show up as multiple coordinates referred to all axes. They have beginning and and end points and solid ones also occupy all points between. (I think it was Michael) made the point that he considers timelike and spacelike axes are not exactly the same and I was exploring the differences, in relation to my point above and also in relation to his comment about movement. You introduced simplified coordinate systems with (I think) one time and one space axis. Any such are continua and could be considered subcontinua of a space having a greater number of dimensions. (I think it was Jon) introduced Flatland, which is a larger subcontuum than yours, but still smaller than our 3 or 4 D world. I found this interesting and tried to incorporate this point in my discussion as well. Perhaps I have brought too many points together and we should consider them one at a time?

Classical EM theory is not quantised so any mention of photons is outside the scope. Discretisation of charge is admissible in classical theory since ions were included. The quantity called electric current' is carried by unspecified charge carriers and is considered as continuous stream of such carriers. This is equivalent to saying that the fluid elements are small enough to be considerd point masses for the purpose of fluid mechanics, so the mechanics of fluids is the mechanics of a continuum. Classical electrical theory including electric and magnetic fields and EM waves is also a branch of continuum physics. Waves are, of course, the bridge between QM and classical physics because they show mathematically how discretised phenonmena can arise naturally in a continuum. I don't think it is possible to discuss energy flows without some more sophisticated mathematics.

Forgive me, but I assumed you were restricting the discussion to a single (1+1) dimension contimuum by the above statement, not (1+1) embedded in a continuum of greater dimensions, which obviously contains many such restricted subcontinua. Please clarify. This is unfair. Of course it is relevent since it was (and still is) a legitimate question about the conditions of validity of your statement. Where is your second observer? In terms of your slant diagram the slanted lines still have a projection on the x axis, which I call their x coordinate. I agree that this projection will vary with the slant. If I zero a coordinate system at the left hand edge of my desk and align one end of my ruler with it, my ruler extends in space from x=0 to x=300, and occupies all points between continuously. If I now move it to the other end it extends from x = 1200 to x = 1500 and occupies all of the points between continuopusly and none of the original points. I am am inviting you to comment on the situation along the time axis, given that the ruler was manufactured in 2010 and will be destroyed in 2015. This is a thread about time so this is entirely relevent.

Well we will have to agree to differ on this aspect, since I believe in calling a spade a spade.

Good evening , MigL Yes and Yes But were your comments with reference to my post#59, that allowed 3/4 D continua (x,y,z,t) or with reference to mypost about Elfmotat's (x,t) continua?

Wouldn't there be a parity difference for pseudovectors like the magnetic field (pseudo)vector if we switched signs? I think this is what Sensei was getting at.

No, that was not the question posed. I stated that as a fact, with some backing reasoning. Given that statement as true I posed a question concerning the effect of that on movement of physical bodies. This question has nothing to do directly with special relativity. Your grid presentations are interesting though, as I have not thought in those diagonal terms. Thank you. However your (1+1) or (x, t) grid does beg the question Where would the the second observer be travelling? Since there is only one x axis and it is already occupied by michael and myself, how would she get past?

So how does that affect my comment?

Just noticed this, Do you mean Jersey, America or Jersey, Europe? Could it have been residue from a furnace? In your yard? Builders used to import clinker as aggregate under slabs. How much of the stuff is there?

Thank you, Jon, I had not heard of the specious present, but it is not what I meant. There has been some discussion of 'objects' moving (or being moved) in space by changing their x (and y and z) coordinates. There is no physical object that I know of that can be attributed to a single x or y or z coordinate ie no physical object has zero length, but occupies a connected segment of space. For instance when I move my 18" screen across the desk I move one side and the other and everything in between. I was seeking a corresponding statement in time for "movement" in time.

Do you live in a volcanic or formerly volcanic area? Could well be pyroclastic volcanic tuff. https://www.google.co.uk/search?hl=en-GB&source=hp&q=volcanic+tuff&gbv=2&oq=volcanic+tuff&gs_l=heirloom-hp.1.0.0l10.1141.5797.0.6672.13.13.0.0.0.0.188.1342.1j10.11.0....0...1ac.1.34.heirloom-hp..2.11.1342._QPfxH-joyM

I note that no Time Lord here has attempted to answer my post#59 Ask The Doctor.

Interesting iterative approach, Mondie. Looks promising.

This is where you need to clearly distinguish between the predictions of QM and classical electrodynamic wave theory (EWT). It is classical EWT that predicts the electromagnetic emission from accelerating charged particles. As such there is no quantisation, the waves are freely emitted. E and H fields at are generated at right angles to each other such that Where E and H are both proportional to the acceleration (a) and the charge (e) and inversely proportional to the distance from the charge ® [math]E,H \propto \frac{{ae\sin (\varphi )}}{r}[/math] phi is the angle made between the direction r is measured in and the direction of acceleration. According to this model, the electric and magnetic fields are always perpendicular to the direction of propagation and move with velocity c. Further because of the sine term they vary in intensity from zero in the direction of propagation to a maximum at right angles to it. I stress again there is not quantisation of these fields. The above is OK for charge speeds small compared to c but needs to be modified for speeds a significant fraction of c. This leads to an apparent energy and mass gain and quantisation effects. You might also find the following non mathematical explanation as to why a single accelerating charge should classically radiate EM waves. Consider a single charged particle travelling between A and B. The faster it goes the greater the steady current it is equivalent to. So if it is accelerating then that current is not steady but increasing. The magnetic induction is proportional to the rate of change of current. So as the particle accelerates, the equivalent current increases, which in turn causes a changing magnetic field. A changing magnetic field gives rise to a (changing) electric field. A changing electric field gives rise to a changing magnetic field. And so the wave is born.

Well your answer is correct, I didn't wade through your maths yet. Well done.

No, No, a thousand times No. Torque is not a force. Torque is an entirely separate effect. Mostly it is the result of a force, but there are other agents that can apply torque as in a Wankel engine. When considered in conjunction with a force, torque is the product of the magnitude of that force and a distance, called the lever arm. This is more difficult than and often confused with work = Force x Distance. A simple way to distinguish is that no (zero) work is done at distances measured at right angles to the line of action of the force. Work is force times distance measured in the direction of that line of action. (You have discussed this in other threads) Torque, on the other hand, is Force times distance measured at right angles to the line of action. We know (I have just said) this the work calculated this way is zero so torque is not work either. That is enough for now.

You draw a diagram to help yourself, not me. So just so long as you draw them. It is useful, but not esential to post a diagram with the question. So you could use paper. They could be not pretty, as mine are not.

Yes the extra distance walked is 2y. I'm sorry I saw this quickly and thought you had 2 equations in x and y I didn't realise that the second was just 120 times the first. So you have one equation Time driving plus time walking = total travel time. On the second occasion this equation still holds, but the times are different. They are different because he spends more time walking than before and less time driving. We know he walks three times as far so, as you said, the extra distance walked is 2y. This extra distance he walks is distance he does not drive so the distance he does drive is (x-2y) I will keep repeating this to you. Draw a diagram it is easy to see then. You should now be able to form your second equation in x and y.

Rest assured, many misunderstand torque. I am not even sure if torque is the appropriate quantity for what you want, which is why I asked Just ask your question in ordinary words and don't try to use technical terms. Allow others to introduce and explain technical terms and see how they use them. And, of course, ask for an explanation if they use a term you don't know. But don't guess.