exchemist

Agree with @studiot that a piece of information seems to be missing from the problem, in the way you describe it. You don't say over what period of time the deceleration occurs. Without that, you can't know if the deceleration was gradual, due to a small force applied for a long period of time, or sudden, due to a large force applied over a short period.

Well by now you know my view: I suspect these are just semi-classical fictions, with no observable consequences.

I think the technical term for this is "clutching at straws."😀

I was sort of hoping my example of Chicago might deter him. I have actually seen that example used by flat-earthers elsewhere, as "proof" the lake is flat. So I thought I would pop that bubble before he had a chance to refer to it. The psychology of these people is what intrigues me. I suppose it may just be contrariness: a determination to be agin everyone else, just for the hell of it. But it is very strange. Makes QAnon look normal - almost. But I digress.......

Yes it is now just about entirely populated with nutcases and cranks- and not even interesting cranks, at that.😄

How do you account for the momentum of a photon in your model? Does that belong to the wave (difficult with a transverse wave, I'd have thought) or to the photon "corpuscle" - which does not move?

That's interesting. In the desert I'd expect an inferior mirage, e.g. the sky being seen as at ground level, so I'd have thought you would each see the other lower than they really were. Or was this at dawn, with cold ground?

OK I see, thanks for the explanation. Well, it's been almost a month but maybe our poster will return and enlighten us....

That's rubbish and I've already explained why. Twice. If you still haven't seen the point, I'm not going to spend more time on this.

This makes no sense. If as you say "the momentum of the eccentric mass along the vertical axis would be cancelled by the momentum of the rest of the system at any instance", then what you have is precisely a vibrating system. Every vertical motion of the eccentric mass is compensated by an opposite motion of the frame. So when the mass moves up, the frame moves down, and when the mass moves down, the frame moves up. What is that if not vibration?

You don't seem to understand mechanics, certainly. You appear to have got hold of a wrong idea, namely that no freely floating system can vibrate. But of course it can. If you have a spring, in free fall in space, say, that has been set vibrating by some means, it will continue to vibrate. Most molecules of a gas at normal temperature are free floating and vibrating. In the case of non-rigid bodies, Newton's Laws only tell you that the centre of gravity (centre of mass) will continue at constant speed in a straight line if no external forces operate. In this case, if your rotating system, with its eccentrically mounted mass, were freely floating, the frame would describe a circular oscillation, opposite to that of the eccentric mass, such as to keep the CG motionless. By attaching springs, a damper and a vertical guide with rollers, you are preventing it from doing that freely. Constraining it involves applying forces, which accelerate the CG first in one direction and then in another. The rollers, the springs and the damper all exerts forces on it. If they did not, there would be no point in them being there.

I'm not with you. There is obviously an unbalanced rotating mass. What's the issue? Later: Or are you asking how a system with no - apparent - exterior force acting on it can vibrate? If that is what you mean, I think the thing to consider is the centre of gravity of the system. If it were not constrained by the setup shown, the system would move such that the CG did not accelerate. Because it is asymmetric, keeping the CG in one place would involve parts of the system moving as the rotating mass rotates. But this is prevented by the side guides, springs and damper constraining it. So these guides will exert forces on it as the eccentric mass rotates. So exterior forces do act on it after all. P.S. Are you training to be a washing machine designer or something? 😀

There are several misconceptions in what you have written. Firstly the shift in wavelength as one looks at more distant objects is a red shift. You are describing a blue shift. What happens is that the wavelengths get longer (=lower frequency) at longer distances, which shifts the yellow to the red and the blue to the green etc. Secondly, the cosmological red shift is not actually a Doppler shift but is caused by the expansion of space itself stretching out the waves. Thirdly, dark matter is so-called because it appears neither to emit nor absorb radiation at any wavelength. Astronomers are not so silly as to have only looked at the visible range of the spectrum. So dark matter really is dark. It is not just something to do with emission being red-shifted.

What transition state, in what process? And what do you mean by an open or "exploded" transition state? It's a bit hard to comment without any information about this .

Yes, I think the term "neck" is used for the extinct eroded form, whereas a plug may be either extinct or just a blockage in an active volcanic conduit, as you say.

Close to the surface of a large body of water, it is very common to have an inversion, whereby the cool water cools the air immediately above. So then it would not be true that the temperature decreases upwards within the layer. The opposite would be the case. For example this explains why Chicago is sometimes visible from a point 60 miles way on the far side of Lake Michigan. It is what is called a superior mirage, and its cause is the bending of light in an inversion layer above the lake: https://www.abc57.com/news/mirage-of-chicago-skyline-seen-from-michigan-shoreline

Domes would be the most dangerous. A dome signifies extremely viscous magma, typically "acid", with lots of silica. Volcanoes with this feature are notorious for eruptions in the form of pyroclastic flows (nuees ardentes). La Montagne Pelee is a classic, as is La Soufriere, currently going off in St Vincent. In the terminology I am used to, a volcanic neck is the exposed solidified magma plug (a sort of dyke) left after the erosion of an extinct volcano. So that would be 100% safe. But I admit my terminology may be out of date.

This article seems to be from mid-2019. Is what sense is it "new", then? And what is troubling about the discrepancies? Aren't they just intriguing? To the right sort of person, I mean.

Duplicate of thread started by @joigus last Friday: https://www.scienceforums.net/topic/124936-billion-year-old-fossil-reveals-missing-link-in-the-evolution-of-animals/

Can you cite examples?

Hmm, I see. In that case we may want to be careful how responses are dealt with, so as not to provide, inadvertently, ammunition for a disinformation video later, as apparently happened last time.

It's the same group, by the look of it, including some person called Bob Knodel. They seem to have a glossy website called FECORE on which various "projects" are described, connected with investigating the curvature of the Earth. Knodel was I think involved in the Lake Balaton caper. But, be that as it may, I have my own evidence the Earth is flat. If it were round, people in New Zealand would be upside down. Well, I've been there, and I can tell you they are the right way up. So there.

Then the question becomes a different one, viz. what limits are there to the rate of pressure change the human body can withstand, or something like that. So far as I know, the most sensitive part of the body from the point of view of pressure changes is the ear. The middle ear equalises pressure with the environment via the eustachian tube, which is linked to the nasal sinuses and is very narrow, with a sort of semi non-return valve in it, to encourage the removal of any mucus discharges etc. To pressurise the middle ear, air must go the "wrong way" through this non-return valve, leading to the sensation of deafness, relieved by swallowing, that we are all familiar with in a descending aircraft. Swallowing allows the non-return valve to open and allow air in "the wrong way". If you increases the pressure too fast, you experience deafness, as the eardrum becomes stretched by the pressure difference, followed by pain as it is further stretched. The eardrum can easily rupture if enough time is not allowed for the ears to "pop" and thus transfer the increased pressure via the eustachian tube to the other side of the eardrum. Some people have difficulty equalising the pressure, especially if they have a cold or other inflammation of the sinuses. To you have to go carefully or you can inflict considerable pain and make people go deaf.

OK, then I can't answer that for sure. But seeing as borate is sold as a buffering agent, it looks to me as if using it may make use of HCl unnecessary. But you would need to check with a supplier of borate, I guess.

This is a silly question.