Talk:International System of Units/Archives/07/2016

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Suggestion for improving the diagram displaying the interrelatedness of the seven basic SI units

SI Units definition dependencies

I don't know how to make a picture like the one already in the article, so I'll describe what I mean. Write 'm', 's', 'kg', 'mol', and 'K' vertically. Then add 'A' on one side of 's' and 'cd' on the other side of 's'. Then add the arrows of dependence. The result is symmetrical with no crossed lines, whereas the current image is not symmetrical at all and has several crossed lines.69.135.193.98 (talk) 10:04, 5 December 2014 (UTC)

I don't think the crossed lines are an issue. They are clearly arrows, I can't see how someone misreads them at the crossings. Then, the circle nicely supports the notion of independent quantities, no preference or priority. (if there is a sequence on the circle with less crossings, that would be good).
I even dislike the presentation with arrows. They are correct, but it undermines the notion of "independent quantity". (Ampere is not solely expressed in metres; that would make ampere be derived). For a top-level topic, the arrows could go. In a section, this partial dependency can be described, with arrows. -DePiep (talk) 10:50, 5 December 2014 (UTC)
For example, position the kg between A and mol. Less crossings. -DePiep (talk) 10:52, 5 December 2014 (UTC)
Ampere (a base unit) is defined relative to the newton (a derived unit). This should be enough to prove that base/derived classification may be useful in dimensional analysis (or whatever criteria they used to select which units are base or derived), but it's not always representative of definition dependencies.

What is the actual definition of S.I unit #Ajay1979 15:55, 27 July 2016 (UTC) — Preceding unsigned comment added by Adtya Sinha (talkcontribs)