John Cuthber
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Everything posted by John Cuthber
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Was that meant to be some sort of answer to the question Strange had asked?
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It's never a good sign when someone says "I want to do this" and cites a clip from an action movie. Also Nothing will stand a million K.
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Can anyone tell me about light-resistant materials?
John Cuthber replied to AmethystFloris's topic in Classical Physics
Metals block light very effectively (unless they are extremely thin) So, a small metal box (with some padding) would do the job of keeping your B12 bottle in the dark. The photography stores used to sell opaque bags of various sorts for handling and string photographic film, but in these days of digital imaging, I don't know if they are still on sale. I'm sorry, but none of that makes much sense. -
That's not a good cavity. This is an article about deliberately absorptive cavities with time constants over a thousand times longer. https://en.wikipedia.org/wiki/Cavity_ring-down_spectroscopy Though it's still well below 1 second. (As an aside, I suspect the LIGO cavities would have a ring down time constant of over a second; that's a really good cavity, but not terribly practical.) More importantly, back at the topic. Isn't "almost infinite" the reciprocal of "practically nothing"?
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Why do shapes with the same area have different perimeter?
John Cuthber replied to King E's topic in Mathematics
You can even have something that's got a finite area, and an infinite perimeter, but that can be enclosed in a finite "box" (or drawn on a finite piece of paper). https://en.wikipedia.org/wiki/Koch_snowflake -
Why do apples fall rather than lift off the ground?
John Cuthber replied to geordief's topic in Relativity
Because the ground got there first, by falling. If apples "fell up" then the ground would too. It would be on the ceiling, but the apples would still land on it if you let go of them. -
Methanol (Used to denature industrial alcohol) is toxic by skin absorption. So, you don't need to drink it for it to be a potential problem. On the other hand: https://en.wikipedia.org/wiki/Methanol_toxicity#Treatment Also, at the moment https://www.thedrinksbusiness.com/2020/03/the-distilleries-and-breweries-and-drinks-groups-making-hand-sanitiser/
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Unless it isn't. https://en.wikipedia.org/wiki/Rubbing_alcohol
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Interesting phrase in a post where you dismiss someone's view without offering any reason to say that the view is incorrect Would you like to borrow a mirror?.
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Srsly..?
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Oops! Boils at 1465, but the point still stands. It has a boiling point, so it doesn't decompose. Yes, notably, if it decomposed to form chlorine, it wouldn't have a boiling point. A matter of definition, but the solid is composed of a lattice of ions. It's already ionised as a solid. To whom is this apparent? It's ionised as a solid and as a liquid. In the solid form, the ions are not mobile. In some other compounds, even the solid conducts by the movement of ions. https://en.wikipedia.org/wiki/Rubidium_silver_iodide https://en.wikipedia.org/wiki/Silver_iodide (Above 420K) Because it's factually incorrect. Scaremongering, (deliberate or accidental) doesn't help anyone.
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How could salt have a boiling point of 883C if it fell apart when it melts at 801?
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No you won't.
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My analysis is that you just invented the pavement cafe.
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Is this related to your interest in musical instrumnts?
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"Is that the kind of example you want people to follow" is a question about epidemiology, not politics. It's obvious that the scientists, like any sensible people, would say "No, it isn't". That's got nothing to do with politics. There would have been no loss of "impartiality" involved in answering it. But Boris didn't let them answer because it made his friend look like an idiot.
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Line Graph for a Solution which has Three Concentrations?
John Cuthber replied to CreativeKick's topic in Chemistry
I'm not sure what you are looking for, but would something like this work https://en.wikipedia.org/wiki/Ternary_plot if you colour coded sleep duration? -
Electric conductivity of suspended particles
John Cuthber replied to mcspencah's topic in Homework Help
It's certainly odd. I'd have expected the opposite effect. I can think of one possibility. If the unfiltered juice contained intact cells and those were broken during the filtration process then it's possible that their contents were less conductive than the surrounding liquid. That's possible, but seems unlikely- I'm not sure how you would test it. Does it get hot during filtration? Is it being filtered on an industrial scale- could you try with a smaller rig- say a laboratory scale with a flask, funnel and filter paper? -
Electric conductivity of suspended particles
John Cuthber replied to mcspencah's topic in Homework Help
Is anyone actually extracting juice from potato fruit? -
A fog in a vacuum is impossible. There's nothing to hold it up.
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It might be worth explaining the bizarre unit- the "inch of vacuum". It is, as I said, like trying to describe the thickness of a coin by measuring the difference between that thickness and the width of your thumb. The original idea was fairly simple. You got a mercury filled barometer. http://www-mdp.eng.cam.ac.uk/web/library/enginfo/aerothermal_dvd_only/aero/fprops/statics/node15.html, Then you connected the top of it to your apparatus. The better your pump was, the more it pulled the mercury up. And if your use for a pump was pulling water out of a mine shaft, that's probably as good as it needed to be. You could pull water roughly 13 times further , because it's 13 )or so) times denser than water. The problem is that the pump doesn't pull the mercury up- the atmosphere pushes it up- and the atmosphere is variable.. Well, that's still OK if you need to know if your pump is pulling water out of a mine, because the head of water is also affected by the atmosphere. But, if you want to get a reasonably accurate measurement, you can't use the atmosphere as a reference point. (OK, technically, you can- if you measure it accurately). If the actual atmospheric pressure varies by an inch of mercury, that isn't going to make much difference to the mine pump. A change between 20 inches and 21 isn't worth worrying about. But, if you are actually working with a pressure that's less than an inch of mercury, your "reference" point varies so much that you can't tell if your pressure is positive or negative (well- it' can't really be negative, but that';s what the gauge.would show). None of that will actually help answer the OP's question. Because the question is like saying "my antique clock keeps time to +/- 30 minutes a day. IS that good enough?" Good enough for what? If the OP ever actually tells us what question they want to answer, we might be able to answer it.
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Interesting question of definition; does a diamond count as organic, or inorganic? Some definitions include CH bonds... Anyway, I think quartz is probably the commonest inorganic macromolecule. Molybdenum blue is one of the oddest https://pubs.acs.org/doi/pdf/10.1021/ja512758j
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And the answer is that it depends what you are trying to do. How did you imagine that we could answer the question without knowing that? It's worse than that. It's like asking how thick a coin is by expressing is as "How much thinner than a thumb is it?". Which part of "impossible" did you not understand?
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If the atmospheric pressure is the so called "standard" of 760 mmHg it is impossible to get 30 inches of vacuum.