Talk:Q12507

defining formula (P2534)

ru: Failed to parse (MathML с переходом в SVG или PNG (рекомендуется для современных браузеров и инструментов повышения доступности): Invalid response ("Math extension cannot connect to Restbase.") from server "/mathoid/local/v1/":): {\displaystyle V = \frac{4}{3} \pi \cdot r^3}

fr: Failed to parse (MathML avec SVG ou PNG en secours (recommandé pour les navigateurs modernes et les outils d’accessibilité): Invalid response ("Math extension cannot connect to Restbase.") from server "/mathoid/local/v1/":): {\displaystyle V = \frac{4}{3} \pi \cdot r^3}

en: ok --Fractaler (talk) 12:29, 22 November 2016 (UTC)

Unit?

How to understand this? --Infovarius (talk) 19:16, 11 March 2021 (UTC)

Change link for Dutch Wikipedia

I think the link for the Dutch Wikipedia should be changed from https://nl.wikipedia.org/wiki/Bol_(lichaam) to https://nl.wikipedia.org/wiki/Sfeer_(wiskunde), the concepts were muddled in the pages in the past, but have been seperated now. I can't do this however, as the page is protected. Yodo9000 (talk) 11:32, 24 February 2022 (UTC)

@Yodo9000:  Done --Epìdosis 14:10, 24 February 2022 (UTC)

@Yodo9000: well, nl:Sfeer_(wiskunde) fits perfectly well to n-sphere (Q306610) (too?). Why not to keep it there? --Infovarius (talk) 15:18, 25 February 2022 (UTC)

@Infovarius Yes I agree, it can be kept there as well, if it is technically possible, but https://en.wikipedia.org/wiki/Sphere was first linked to https://nl.wikipedia.org/wiki/Bol_(lichaam) which had become incorrect. Yodo9000 (talk) 16:45, 25 February 2022 (UTC)

Volume of a sphere

V=(√(3.2)radius)³ Gmac4247 (talk) 16:12, 29 January 2024 (UTC)

Not exactly. --Infovarius (talk) 18:32, 29 January 2024 (UTC)

Exactly. Gmac4247 (talk) 15:07, 5 February 2024 (UTC)

Please don't advance your personal point of view on this project, if you have good reference (in academic magazine) then show it. --Infovarius (talk) 09:57, 7 February 2024 (UTC)

I regard my personal point of view irrelevant, but the equation V=(√(3.2)radius)³ factually correct. I don't have any magazines. Gmac4247 (talk) 18:03, 20 February 2024 (UTC)

The V=4/3*π*r³ formula was derived by comparing the sphere as a set of disks to a cube.

That method is not totally accurate and can produce an under- and an overestimated value.

4/3*π*r³ is the underestimate, which is invalid without the overestimate.

I have also measured. If I take 2 similar glasses, fill one full of water, put a golf ball with radius of 2 cm in it, then carefully pour the water into the other glass, the volume of the water will be less by the volume of the golf ball. Then I fill up the glass using a 4 cl glass. According to "4/3*π*r³" the volume of the ball should be about 3.35 cl, according to (√(3.2)r)³ it's about 4.58 cl. The water poured from the 4 cl glass filled it almost full. If the volume of the ball was 3.35 cl, the water from the 4 cl glass should had spilled. I use metrics, but that's irrelevant. The ratios are the same using inches. This method is accurate enough for reference. You can try this at home.

"description: round, rotationally symmetric shape of the 2D surface of a ball in 3D space" => V=(√(3.2r²))³

Gmac4247 (talk) 08:46, 20 April 2024 (UTC)