https://www.explainxkcd.com/wiki/api.php?action=feedcontributions&user=108.162.219.176&feedformat=atomexplain xkcd - User contributions [en]2024-03-28T19:07:47ZUser contributionsMediaWiki 1.30.0https://www.explainxkcd.com/wiki/index.php?title=759:_3x9&diff=205539759: 3x92021-01-29T15:06:37Z<p>108.162.219.176: Edited pronouns in paragraph 4 to be gender neutral</p>
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<div>{{comic<br />
| number = 759<br />
| date = June 28, 2010 <br />
| title = 3x9<br />
| image = 3x9.png<br />
| titletext = Handy exam trick: when you know the answer but not the correct derivation, derive blindly forward from the givens and backward from the answer, and join the chains once the equations start looking similar. Sometimes the graders don't notice the seam.<br />
}}<br />
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==Explanation==<br />
In college courses with a very large number of students (picture the huge, tired, amphitheater-style lecture halls shown in any movie or TV show about college), teaching assistants are often employed to help the professors grade student work. In math and science courses, students are expected to solve the problems and show their work as supporting evidence. Due to the high volume of work to grade, whether it's being done by the professor or a TA, the grader will get lazy and look for correct answers and the existence of work without checking that the work is accurate.<br />
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The math shown in this comic switches from √ being square root notation to it being division notation midway. That is an illegal operation.{{Citation needed}} But the correct answer is reached anyway, because 27 is the correct answer to 3 &times; 9, 3√81, ''and'' 81 &divide; 3.<br />
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More generally, this pattern holds true for any number and its square; namely, 𝑥𝑦 = 𝑦&sup2; &divide; 𝑥 whenever 𝑦 = x&sup2; &nbsp; (... namely, x*y = y^2/x whenever y=x^2) .<br />
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The title text describes another technique usable when you remember the answer but not the calculations. It requires modifying the equation and the answer at the same time, hoping that at one point they'll look similar. Some students picture every step in the calculations, others skip some, as they seem obvious to them. Merging the equations once they look similar may trick the examiner into thinking that the step between them is obvious to the student, even if they ARE checking the calculations. The side effect (not mentioned) is that while doing this, you may actually realize what the calculations should be.<br />
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Alternatively, the title text could be a description of the calculations shown in the comic.<br />
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==Transcript==<br />
:[A problem is given on an arithmetic test: "4) 3x9=?". In handwriting, the student's work follows. The student has accurately reformatted the question as 3 times the square root of 81, which visually resembles the long division problem of 3 divided into 81, and then solved the latter to get 27 — the correct answer to both.]<br />
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{{comic discussion}}<br />
[[Category:Math]]</div>108.162.219.176https://www.explainxkcd.com/wiki/index.php?title=2413:_Pulsar_Analogy&diff=2049712413: Pulsar Analogy2021-01-19T00:57:31Z<p>108.162.219.176: The pulsing is produced in both cases by the beam flashing across the eyes.</p>
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<div>{{comic<br />
| number = 2413<br />
| date = January 19, 2021<br />
| title = Pulsar Analogy<br />
| image = pulsar_analogy.png<br />
| titletext = The #2 cause of astronomer hand injuries is trying to do vector math when the second axis points off to the right.<br />
}}<br />
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==Explanation==<br />
{{incomplete|Created by a PULSAR. Please mention here why this explanation isn't complete. Do NOT delete this tag too soon.}}<br />
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{{w|Pulsar}}s are dead stellar cores that produce fast-spinning beams of radiation. Ponytail, an astronomer in this comic, explains a pulsar's fast rotation with an analogy about a tape measure retracting. This analogy could be seen as inaccurate, considering that the tape measure starts to rotate because the spring imparts a torque on the body of the tape measure. Pulsars rotate at their extreme speeds because of the conservation of momentum, which is similar to why a tape measure rotates if the tape and the body are considered together as a unit. As a star collapses into a pulsar, its natural rotation rate is greatly amplified by its shrinking moment of inertia.<br />
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That's probably totally wrong. But regardless, so is the idea of a laser measure being "exactly" like the emissions of a pulsar, which, although both pulse (and for the same reason), are produced in entirely different ways and are simply helping the mind hold the concept.<br />
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Retractable tape measures often have a belt clip on the side that doesn't have the label. The clip gives that side fewer points of contact on a flat surface than the flat label side would, and will spin longer because of less friction. Snapping the tape down will shorten the measure's lifespan, however: If the rivets that hold the bracket at the end of the tape shear off, the tape will tract entirely inside the measure body, and will be useless.<br />
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==Transcript==<br />
{{incomplete transcript|Do NOT delete this tag too soon.}}<br />
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{{comic discussion}}</div>108.162.219.176https://www.explainxkcd.com/wiki/index.php?title=Talk:2392:_Cyber_Cafe&diff=202568Talk:2392: Cyber Cafe2020-12-01T20:43:30Z<p>108.162.219.176: </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 />
Is it worth noting that this was posted on Cyber Monday? [[Special:Contributions/162.158.75.70|162.158.75.70]] 21:57, 30 November 2020 (UTC)<br />
:Yes! That's almost certainly relevant. [[User:Barmar|Barmar]] ([[User talk:Barmar|talk]])<br />
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Unrelated to cybercafés, but why is the edit link the viewed-outside mauve instead of the viewed-wiki violet? <span style="font-family:Palatino,serif">[[User:Bubblegum|<span style="color:#00BFFF">bubblegum</span>]]-[[User_talk:Bubblegum|<span style="color:#BF7FFF">talk</span>]]|[[Special:Contributions/Bubblegum|<span style="color:#FF7FFF">contribs</span>]]</span> <span style="font-family:Palatino">04:13, 1 December 2020 (UTC)</span><br />
:Which edit link(s)? The 'faux tab' ("Read | Edit | View History", etc) the "*TITLE HEADER* (Edit)" or A.N.Other? Is it something specific to your own browser stylesheet? Or set by your Wikilogin? For me (simple IP as I am) the only links of different colours (passing over your own .sig, Bubblegum) are the Main page/Latest comic/Community portal/xkcd.com links in the sidebar((*)), and those are in the universal "visited page" hue (because I have visited these) and all other non-image link text are in the colour of universally standard yet-to-visit link colour that is probably the same as NCSA Mosaic originally established/adopted (though I don't know if that's because it's set by the wikicode/styles or fallen back to default). ((* - plus, now, the "add a comment!" link and also the cybersex one, as a random in-explanation link I tested going to while writing this reply.)) [[Special:Contributions/162.158.158.43|162.158.158.43]] 05:03, 1 December 2020 (UTC)<br />
::The "edit this page" link in the incomplete transcript template. <span style="font-family:Palatino,serif">[[User:Bubblegum|<span style="color:#00BFFF">bubblegum</span>]]-[[User_talk:Bubblegum|<span style="color:#BF7FFF">talk</span>]]|[[Special:Contributions/Bubblegum|<span style="color:#FF7FFF">contribs</span>]]</span> <span style="font-family:Palatino">18:02, 1 December 2020 (UTC)</span><br />
:::(Moved into the right spot in the conversation.) Well, it's class="external text", which sounds like it'd do what you say it does. (Mauve? Maybe, but I'd not call it that.) Must just come from the template it inserts from. [[Special:Contributions/108.162.219.176|108.162.219.176]] 20:43, 1 December 2020 (UTC)<br />
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"Cyber" is 'dated'? Well, I suppose it has been around as a popular term for a while, probably even before Gibson (and long-standing Internet Cafes 'round here now seem more to be rebranded as eSports hosts, because ''almost'' everyone who cares for one has an Internetted-device on their desk, kitchen table, maybe in their pocket, but a good well-maintained machine for the latest faddy FPSing or any satisfyingly tactile wheel/pedal controller seems to be what they can still offer up, almost arcadian...) but I don't think in the last thirty years I ever said "I'm in Cyber", even though I probably am by today's lingo (old fuddy-duddy as I am, I just say I work "in computing", if anybody has had to feign social interest in me to ask - and then reel off some of my actual sub-specialities if they foolishly indicate a desire to know more). Nor have I ever used such a café, in any capacity, but probably more from a "safe hex" standpoint (malware remediation and cracker-thwarting having been a big part of my career, for several years either side of the Millenium) than this year's issue with a certain non-software virus... [[Special:Contributions/162.158.158.43|162.158.158.43]] 05:03, 1 December 2020 (UTC)<br />
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"this comic suggests that [cyber] sounds dated" Maybe that was so long ago that some people don't remember it. In the 90s, everything was cyber. The internet was "cyberspace". This weird, nerdy, futuristic thing. Then it became mainstream and the term mostly vanished. And since then "cyber" was very dated. It only stuck around in some words like "cyber cafe". [[Special:Contributions/162.158.94.186|162.158.94.186]] 11:32, 1 December 2020 (UTC)<br />
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The UK Government still thinks 'cyber' is in use in 2020: https://www.standard.co.uk/news/uk/fatima-ballet-dancer-job-cyber-government-campaign-a4568641.html <br />
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You young kids etc etc. First use of "cybernetics" is from "Cybernetics: Or Control and Communication in the Animal and the Machine is a book written by Norbert Wiener and published in 1948." (Wikipedia). First use of "cyborg" is from 1960 , Manfred Clynes and Nathan S. Kline. Pretty much all compound "Cyber-$NOUN" words derive from "cybernetics." [[User:Cellocgw|Cellocgw]] ([[User talk:Cellocgw|talk]]) 12:31, 1 December 2020 (UTC)<br />
[[Special:Contributions/141.101.98.158|141.101.98.158]] 11:47, 1 December 2020 (UTC)</div>108.162.219.176