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John Cuthber

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Posts posted by John Cuthber


  1. 1 hour ago, Technix540 said:

    Does anybody have any tips on what type of reaction this is?

    Imaginary, HSiPr does not exist.

    1 hour ago, Technix540 said:

    but this can't simply be a protonation of the double bond,

    That's a fair point given...

    "HSiPr , Base"

    Protonation seems unlikely

    What's your view on a deprotonation of something by that base?


  2. 7 hours ago, Halc said:

    The purpose of the sub is not these things.  It can use GPS if navigation is a goal at all.

    Only at depths where it could navigate by the stars in the way that sailing ships did.
    Attenuation of 1.5GHz GPS signals by water  will be worse than attenuation of light.


  3. Interesting discussion.

    Either a supersonic submarine is possible, or it isn't.

    If it isn't possible, what does happen if I put an arbitrarily powerful rocket on the back end of a pointy lump of oil - filled metal with an overall density equal to sea water?

    Setting aside the practically, imagine that I can crank up the power as far as I like.

     

    As far as I can tell, if I put enough power into it, the thing will go supersonic- probably not for long before it's eroded away to nothing.

    A slightly more practical factor.

    The cavitation at the back of the craft may be somewhat offset by the exhaust gases from the rocket.


  4. 1 hour ago, Ghideon said:

    (1) sunny_day  garden_wedding

    Odd.

    What if there are no couples wishing to get married that week?

    What if it's sunny, but also very cold?

    It is currently sunny in my garden but I don't see any weddings.

     

    Translating human language is difficult- partly because people are enormously clever and can cope with this level of ambiguity.


  5. English is not the only culprit

    Un sot avait pour mission de faire parvenir le sceau d'un seigneur à son roi.

    Il le mit dans un seau et partit à cheval.

    Le cheval fit un saut et les trois (word) tombèrent.


    How do you spell the word in brackets which sounds like the English word "so" or, if you like, "sew".


  6. 14 hours ago, Mitko Gorgiev said:

    The weakening of the strength is symbolically represented by the different shades of gray (figure a).

    It isn't represented very well.

    A set of semi-circles would be a better picture than a set of bars.

    This has been pointed out to you before.
    You persistently troll your unrealistic view.

    14 hours ago, Mitko Gorgiev said:

    This means that the strength of the magnetic field is the same in every point of the interspace (figure c).

     

    Again, that's simply not true. It it was, the designers of NMR machines would have a much easier time.

    14 hours ago, Mitko Gorgiev said:

    The magnetic field is homogeneous in terms of strength, but it is not homogeneous in terms of polarity.

    If you think about that, you will realise it is nonsense

    It can't go from + to - without going through zero And if it is zero in some places, but not others, it is not homogeneous.

    And, because you don't have a sensible model of what the field is like, your ideas about what would happen if you moved a conductor through that field are also wrong.


     


  7. On the whole, this is a bad idea- lots of toxic waste for no great purpose.

    Never bath in Irish Stew,
    It's the most illogical thing to do,
    But should you go against my reasoning,
    Don't fail to add the appropriate seasoning !

    Author: Spike Milligan


    OK so, now we have got that out of the way...

    You can dissolve mercury in a solution of iodine and potassium iodide.
    And, if you make that solution alkaline, most metals will not dissolve, so you can filter them off as hydroxides etc.

    If you then add formaldehyde, it will reduce mercury back to the metal and precipitate it. Some other metals will remain in solution.

    So that removes most of the metals from the mercury.

    If you need to ask for details then you don't know enough about it to do it safely- so don't try.

    Distillation works better but is really not a "home experiment" thing.
    Electrolytic purification is an interesting idea, but probably too difficult - and generates lots of mercury waste.

    But the best advice is just don't bother.
     


  8. 13 hours ago, Phi for All said:

    The medium sound could travel in is full of cats who're meowing instead of listening, so you'll never know.

    Not necessarily.

    You could have an infinite number of cats spaced every metre  on an infinitely long line.

    Or 1 cat on each of the intersections of an infinite square array 

    Or even on the apexes of an infinite array of intersections of a 1 metre "3D"  grid.

    The cats in in the last scenario would definitely overheat.
    I think the ones in the first scenario (a line of cats) would be OK on that score.
    I'm not sure about a planar array of cats.


    But there's no problem putting a space between the cats to make room for a listener.
    The big problem would be herding the cats.

     

     


  9. Sensei,

    Did you really read this
     

    20 hours ago, CuriosOne said:

    Something that deals with "vibrations" between "say"  2 machines vibrating on a table affecting "say" a cup on the surface of the table,

    and you want to know which machine has the greater influence on the cup..

    and think that this
     

     

    8 hours ago, Sensei said:

    diffraction grating ($14 on eBay)

    - prism ($10-15 on eBay)

    - single-slit and double-slit ($12 on Amazon)

    - polarization filters ($13 on Amazon) (make sure there are two!)

    - lasers (you should get red, green and blue at least)

    The all these toys will cost you ~$100, and you will be able to make experiments with light at home..

    was going to help?


  10. 3 hours ago, dimreepr said:

    My point stands, how do you know they're unaware of the concept, there's no reason to assume the original concept was irrational.

    If, as seems likely, their thoughts and ideas were subject to various irrational influences, it's rather likely that the outcome was irrational.

    At best, this looks like an accidental debate about what "rational" means.

     

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