https://www.explainxkcd.com/wiki/api.php?action=feedcontributions&user=172.69.22.229&feedformat=atomexplain xkcd - User contributions [en]2024-03-29T01:19:12ZUser contributionsMediaWiki 1.30.0https://www.explainxkcd.com/wiki/index.php?title=2840:_Earth_Layers&diff=3254302840: Earth Layers2023-10-12T00:54:56Z<p>172.69.22.229: /* Explanation */ main use of cork wall lining today</p>
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<div>{{comic<br />
| number = 2840<br />
| date = October 11, 2023<br />
| title = Earth Layers<br />
| image = earth_layers_2x.png<br />
| imagesize = 585x627px<br />
| noexpand = true<br />
| titletext = The Earth's magnetic field is primarily generated by currents in the liquid outer core, though some geophysicists argue that an unexplained mismatch with models suggests that the Kinder toy contains a magnet.<br />
}}<br />
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==Explanation==<br />
{{incomplete|Created by a KINDER SURPRISE - Please change this comment when editing this page. Like this? Do NOT delete this tag too soon.}}<br />
<br />
This comic reimagines the internal structure of the earth, mixing the real geological layers of the planet with fictional ones. Some of the fictional layers are appropriated from the layers of other objects that have cross-sectional diagrams, such as the layers of a piece of fruit, an eyeball, or a building.<br />
<br />
{| class="wikitable"<br />
! Layer<br />
! scope="col"| Explanation<br />
|-<br />
! scope="row"| Lithosphere/Crust (50/50 Blend)<br />
| The {{w|lithosphere}} is any outermost rocky layer of a planet. On Earth it consists of the {{w|Earth's crust|crust}} and any parts of the upper mantle (see below) that do not convect. To say they are two distinct layers that could be blended together is rather nonsensical.<br />
|-<br />
! scope="row"| {{w|Upper mantle}}<br />
| An actual layer of the earth's structure.<br />
|-<br />
! scope="row"| Deep mantle<br />
| A pseudo-correct layer of the earth's structure. There is a layer called the {{w|lower mantle}}, which could be what Randall refers to.<br />
|-<br />
! scope="row"| Filler<br />
| This suggests there is space in the earth that was empty, so the creator(s) added some filler to fill up the extra space.<br />
|-<br />
! scope="row"| Vitreous humor<br />
|Vitreous humor ({{w|vitreous body}}) is the transparent gel inside the eye, located between the lens and the retina.<br />
|-<br />
! scope="row"| Mechanical/HVAC layer<br />
| {{w|HVAC}} is an abbreviation for heating, ventilation, and air conditioning - the system used to heat or cool a building. Tall buildings can have a "HVAC floor" or "utilities floor" between regular floors, like an extra layer.<br />
|-<br />
! scope="row"| Guacamole <br />
| {{w|Guacamole}} is a dip or sauce made from avocados. Originating in the Mayan Empire{{citation needed}}, It often includes onions, tomatoes, and spices. Notably, guacamole is a major component of seven layer dip, and are shown here to be the seventh layer (from the surface).<br />
|-<br />
! scope="row"| Cytoplasm<br />
|{{w|Cytoplasm}} is the "flesh" of both eukaryotic and prokaryotic cells; a jelly-like substance that fills all the otherwise empty space within the cell.<br />
|-<br />
! scope="row"| Cork<br />
|Due to the proximity of the cork layer and the insulation layer, this may possibly be referencing {{w|Cork (material)|cork}}-lined walls, which are used today mostly for high quality soundproofing, but have a [https://www.jstor.org/stable/27135713 a considerable history]. Another potential reference could be the fact that baseballs (another spherical shape) have a layer of cork in them (though it is usually in the center).<br />
|-<br />
! scope="row"| Insulation<br />
|Probably a reference to the {{w|building insulation}} installed in the walls and ceilings of buildings.<br />
|-<br />
! scope="row"| Seeds<br />
|Part of a fruit.<br />
|-<br />
! scope="row"| {{w|Pith}}<br />
|Part of a tree trunk or the thick spongy layer of the skin of a citrus fruit <br />
|-<br />
! scope="row"| Nougat<br />
|{{w|Nougat}} is a family of confections made with sugar or honey, roasted nuts, whipped egg whites, and sometimes chopped candied fruit.<br />
|-<br />
! scope="row"| {{w|Outer core}}<br />
| An actual layer of the earth's structure.<br />
|-<br />
! scope="row"| {{w|Inner core}}<br />
| An actual layer of the earth's structure.<br />
|-<br />
! scope="row"| Secret core<br />
| The "next layer" that is secret and only certain people, like Randall, know about it.<br />
|-<br />
! scope="row"| Kinder toy capsule<br />
| A {{w|Kinder (brand)|Kinder}} toy is a reference to two chocolate egg-shaped confections by the Kinder brand, the {{w|Kinder Joy}} and {{w|Kinder Surprise}}. Both contain small toys within it, though the Kinder Surprise was banned in the US because it exceeds the limit of non-food that can be inside a food item (although it is widely believed that it's because it can be a choking hazard, despite the fact that you'd have to be swallowing a chicken egg-sized confectionery in a single mouthful for that to happen; the toys, on the other hand, may contain brightly coloured small pieces that can pose a choking hazard). Randall's punch line of the comic is that there is a hidden toy at the center of the Earth. The title text elaborates on this further, stating that due to an "unexplained mismatch" with other models, some geophysicists argue that the hidden toy is - or at least contains - some form of magnet.<br />
<br />
|}<br />
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==Transcript==<br />
{{incomplete transcript|Do NOT delete this tag too soon.}}<br />
:The layers of the Earth<br />
<br />
:Lithosphere/crust (50/50 blend)<br />
:Upper mantle<br />
:Deep mantle<br />
:Filler<br />
:Vitreous humor<br />
:Mechanical/HVAC layer<br />
:Guacamole<br />
:Cytoplasm<br />
:Cork<br />
:Insulation<br />
:Seeds<br />
:Pith<br />
:Nougat<br />
:Outer core<br />
:Inner core<br />
:Secret core<br />
:Kinder toy capsule<br />
<br />
{{comic discussion}}<br />
<br />
[[Category:Comics with color]]<br />
[[Category:Geology]]<br />
[[Category:Food]]</div>172.69.22.229https://www.explainxkcd.com/wiki/index.php?title=2509:_Useful_Geometry_Formulas&diff=2174382509: Useful Geometry Formulas2021-09-01T15:16:02Z<p>172.69.22.229: Fixed a spelling mistake</p>
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<div>{{comic<br />
| number = 2509<br />
| date = August 30, 2021<br />
| title = Useful Geometry Formulas<br />
| image = useful_geometry_formulas.png<br />
| titletext = Geometry textbooks always try to trick you by adding decorative stripes and dotted lines.<br />
}}<br />
<br />
==Explanation==<br />
{{incomplete|Created by a STRIPED AND DOTTED TEXTBOOK ILLUSTRATOR. Explain the formulas for each of the areas, and also the correct formula for the 3D object they seems to represent. Do NOT delete this tag too soon.}}<br />
This comic showcases area formulas for four two-dimensional geometric shapes which each have extra dotted and/or solid lines making them look like illustrations for 3-dimensional objects - the first, a simple equation for a circle, the second an equation for a triangle with a semi-elliptic base, the third an equation for a rectangle with an elliptical base and top, and the fourth a hexagon consisting of two opposing right angled corners and two parallel diagonal lines connecting their sides. In each case, only the outline of each shape is measured.<br />
<br />
Such illustrations are commonly found in geometry textbooks, which need to depict three-dimensional figures on a two-dimensional page. They use slanted lines to indicate edges receding into the distance, and dashed lines to indicate an edge occluded by nearer parts of the solid. The joke is that the formulae given here are for the area of each two-dimensional shape within its outer solid lines, not for the surface area or volume of the illustrated 3D object (as would be shown in the geometry textbook). The title text continues the joke by claiming that the dotted lines are simply decorative.<br />
<br />
The illustrations depict the following plane or solid figures, depending on the interpretation.<br />
<br />
<b>Top left.</b>&emsp;A circle (illustrating a sphere) with radius r. The equation for the area of a circle is A = πr<sup>2</sup> as is given below the figure. The surface area of a sphere is 4πr<sup>2</sup> , which is what we would have expected from the figure. The volume of a sphere is <sup>4</sup>/<sub>3</sub>&nbsp;πr<sup>3</sup>.<br />
<br />
<b>Top right.</b>&emsp;An isosceles triangle of height h combined with a semi-ellipse with semiaxes a and b (illustrating a right elliptic cone). The area of the triangle is bh, and the area of the semi-ellipse is <sup>π</sup>/<sub>2</sub>&nbsp;ab. The equation for this area is A = 1/2 πab + bh as is given below the figure. However, if this was in a text book then a=b even if drawn like this, thus the cone has a circular base, in the 3D drawing. Such a "normal" cone has an area A = πb^2 + πbh. (a=b). That cone's volume would be πr^2*h/3. Taking the 3D drawing literal with a≠b then the lateral surface area of a right elliptic cone is<br>2a√(b<sup>2</sup>&nbsp;+&nbsp;h<sup>2</sup>)&nbsp;∫<sub>0</sub><sup>1</sup>&nbsp;√(<sup>a²h²(t²-1)&nbsp;-&nbsp;b²(a²+h²t²)</sup>/<sub>a²(t²-1)(b²+h²)</sub>)&nbsp;dt. The volume is <sup>π</sup>/<sub>3</sub>&nbsp;abh.<br />
<br />
<b>Bottom left.</b>&emsp;A rectangle of width d and height h between two semi-ellipses of semi-minor axis r (illustrating a right elliptic cylinder). The area of the rectangle is dh and the area of the two half-ellipses equals the area of one full ellipse, <sup>π</sup>/<sub>2</sub>&nbsp;dr. The equation for this area is A = d(πr/2 + h) as is given below the figure. For a 3D representation the cylinder has circular base so d = 2r, (not elliptical as indicated in the 2D drawing). Such a cylinder has a surface area of 2πr^2 + πdh. The volume of such a cylinder is πr^2h. Taking the 3D drawing literal with d≠2r then the lateral surface area of the right elliptic cylinder is 4h&nbsp;∫<sub>0</sub><sup>1</sup>&nbsp;√(<sup>1&nbsp;-&nbsp;t²(1-4r²/d²)</sup>/<sub>1&nbsp;-&nbsp;t²</sub>)&nbsp;dt. The volume is <sup>π</sup>/<sub>2</sub>&nbsp;rdh. <br />
<br />
<b>Bottom right.</b>&emsp;A convex hexagon with three pairs of parallel sides and two right angles at opposite vertices (illustrating a rhomboid-based prism). The area of the rectangle representing the front face of the prism is bh. The area of the upper parallelogram is db&nbsp;sin&nbsp;θ. The area of the right parallelogram is dh&nbsp;cos&nbsp;θ. The equation for this area is A = bh + d(b sinθ + h cosθ) as is given below the figure. The surface area of the prism would be 2bh&nbsp;+&nbsp;2db sin θ&nbsp;+&nbsp;2dh. The volume is bdh sin θ. Assuming a 3D shape, θ can be artificially altered by the projection; the assumption could be made that θ is 90 degrees, and sin θ is 1 (and therefore can be eliminated from the formulas), but since θ is marked, such an assumption might not be valid.<br />
<br />
In the history of the development of computer-generated 3D graphics, calculations of the apparent visual area taken up by the projection of a volume may have been useful in occlusion-like optimizations, where each drawn pixel may be passed through many fragment shaders.<br />
<br />
==Transcript==<br />
{{incomplete transcript|Do NOT delete this tag too soon.}}<br />
:[Four figures in two rows of two, each depicts a two-dimensional representation of a three-dimensional object, with solid lines in front and dotted lines behind. Each figure has some labeled dimensions represented with arrows and a formula underneath indicating its area. Above the four figures is a header:]<br />
:Useful geometry formulas<br />
<br />
:[Top left; a 'sphere', or a circle with a concentrict half-dotted ellipse sharing its major axis, with the shared semi-major radius labeled 'r']<br />
:A = πr²<br />
<br />
:[Top right; a 'cone', or a triangle with the base replaced by a half-dotted ellipse. The triangular/conic height is 'h'. The ellipse in place of the base has semi-minor axis 'a' and major axis 'b']<br />
:A = 1/2 πab + bh<br />
<br />
:[Bottom left; a 'cylinder', or a pair of ellipses connected by verticals. The vertical side/edge is shon as height 'h'. The ellipses have semi-minor axis r, in the lower half-dotted ellipse, and major axis d, across the upper ellipse]<br />
:A = d(πr/2 + h)<br />
<br />
:[Bottom right; a 'rhomboid-based prism', or a semi-regular hexagon with identical pairs of vertical, horizontal and diagonal sides, plus three more congruent pairs (one of each dotted) all linking inwards from their own vertex to meet at one of two complimentary points within. The representative horizontal line is marked 'b', a vertical is 'h', a diagonal as 'd'. Between the base horizontal and the lower internal diagonal is a non-'rightangled' angle 'θ']<br />
:A = bh + d(b sinθ + h cosθ)<br />
<br />
{{comic discussion}}<br />
<br />
[[Category:Math]]</div>172.69.22.229https://www.explainxkcd.com/wiki/index.php?title=Talk:2503:_Memo_Spike_Connector&diff=216721Talk:2503: Memo Spike Connector2021-08-17T10:55:50Z<p>172.69.22.229: </p>
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<div><!--Please sign your posts with ~~~~ and don't delete this text. New comments should be added at the bottom.--><br />
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Just made my first ever wiki edit! There was no text yet so I filled in some basic info. I guarantee what I wrote will be removed though :( . Oh well, I tried! [[User:Zman350x|Zman350x]] ([[User talk:Zman350x|talk]]) 15:20, 16 August 2021 (UTC)<br />
:Your first edit inspired me to my own first edit. Maybe at the end there will be a good article made entirely by noobs. :) [[Special:Contributions/172.68.110.115|172.68.110.115]] 16:33, 16 August 2021 (UTC)<br />
::Seems like some parts of your edits have survived, to what seems close to a final version now. Any start on an explanation is difficult so cool that you are now on the editing team ;-) I make a lot of edits, but is not typically the one that makes the actual explanation, more keeping the format and making small improvements --[[User:Kynde|Kynde]] ([[User talk:Kynde|talk]]) 07:20, 17 August 2021 (UTC)<br />
:: :o --[[Special:Contributions/172.69.22.229|172.69.22.229]] 10:55, 17 August 2021 (UTC)<br />
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In restaurants these are not used for orders for the kitchen. Those are usually put on an order wheel or ticket holder, which have clips that the order can easily pulled out of. The spike is at the checkout counter, and it's used after the bill is paid. [[User:Barmar|Barmar]] ([[User talk:Barmar|talk]]) 19:57, 16 August 2021 (UTC)<br />
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Do we want to mention the vampire taps in both the article and trivia? Cause that's how it currently is. [[User:Zman350x|Zman350x]] ([[User talk:Zman350x|talk]]) 21:27, 16 August 2021 (UTC)<br />
:No. Have removed trivia. --[[User:Kynde|Kynde]] ([[User talk:Kynde|talk]]) 07:20, 17 August 2021 (UTC)<br />
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My first comment too! Where it says... "The implication is that any cable can be connected to any other cable as a form of universal adapter/splitter/combiner"... That's not the title text joke. It's that a device like an iPad could also be impaled on the spike, making electrical connection to its innards. It says nothing about cable to cable connections. [[Special:Contributions/108.162.246.18|108.162.246.18]] 21:47, 16 August 2021 (UTC)<br />
:Didn't see this comment until I intervened, under the same impression, but I totally agree. Looked like an orphan comment intended for the pre-titletext 'explanation'. Still valid, and rather than move it I expanded it to fit better where it is. Doubt it'll be the 'final' version, though. (Anecdotal explanation of my thinking: If I put my tablet down on my opened laptop, it'll sometimes 'agitate' the laptop trackpad. Technically I could probably get the tablet to control this inbuilt mouse deliberately through whatever ¿field-effect? is interacting with the ¿capacitative? finger-sensor. I am imagining something like this (only more puncturing!) is what is 'promised' if I impale two otherwise incompatible devices on the same spike. But also lets one connect otherwise incompatible cables to further cables/devices. Like I don't have an ethernet dongle that works with the tablet, but spike them both and I'd be laughing.... Right?) [[Special:Contributions/172.69.54.202|172.69.54.202]] 03:14, 17 August 2021 (UTC)<br />
::The title text is also about old types of cables and not just smartphones and tablet. --[[User:Kynde|Kynde]] ([[User talk:Kynde|talk]]) 07:20, 17 August 2021 (UTC)<br />
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This explanation does not answer the one question I came here to find the answer to, namely why it is named “memo spike.” [[Special:Contributions/108.162.219.79|108.162.219.79]] 03:19, 17 August 2021 (UTC)<br />
:Some (not me, but that's because I've never used one in anger, maybe) seem to call the non-connector thing that the connector is based around a "memo spike". Apparently one can impale successive memos (in a memo-heavy administration job?) upon the spike and then later thread a chord (or treasury tag?) through the holes to perpetuate their 'spiked collection' status. It's possible there are other names (like: thumb-tack <=> drawing pin), but this is how Randall identifies it. Better than "that thing you spike paper onto - but now with ''power!!!111oneoneone''", etc... 'Though YMMV. [[Special:Contributions/141.101.76.253|141.101.76.253]] 03:56, 17 August 2021 (UTC)<br />
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The detail on the free cable end is more clearly visible in the [https://imgs.xkcd.com/comics/memo_spike_connector_2x.png double-sized image version], suggesting that it isn't just a coax. [[User:BunsenH|BunsenH]] ([[User talk:BunsenH|talk]]) 04:28, 17 August 2021 (UTC)<br />
:It is actually the x2 version that is now showed per default on the xkcd page, and thus it is that one that should be used here on xkcd.. ie. the one you are presented with on xkcd. Have uploaded that version to explain now. --[[User:Kynde|Kynde]] ([[User talk:Kynde|talk]]) 07:20, 17 August 2021 (UTC)</div>172.69.22.229