explain xkcd - User contributions [en]

Talk:379: Forgetting

2025-06-01T21:53:07Z

162.158.33.240:

The syntax for pointers in C++ is ''&pointer'' and ''*pointer''. The arrow syntax is used e.g. in PHP. So this explain does need a review. And furthermore it should focus on the assert joke, understandable for non programmers.--[[User:Dgbrt|Dgbrt]] ([[User talk:Dgbrt|talk]]) 18:48, 31 July 2013 (UTC)
:Actually this works in C++ too. (*pointer).property is the same as pointer->property -- 17:58, 31 july 2013 (Time in Florida)
::Do you have a code snippet, maybe this could help me to explain this comic for non programmers.--[[User:Dgbrt|Dgbrt]] ([[User talk:Dgbrt|talk]]) 22:43, 31 July 2013 (UTC)
:::At the moment I don't have a computer, just my phone, but I'll try (so i appologize for any typos in advance, you may correct them)
pair<int, int>* pntr = make_pair(5, 8);
cout << (*pntr).first << endl;
cout << pntr->first << endl; // the same as above
:::: The arrow operator -> is a valid way to access object members using smart ptrs in C++
-- 22:12, 31 July 2013 (Florida)
:I removed PHP as a possible language since PHP variable names start with a $. Zetfr 09:24, 20 May 2015 (UTC)
::IT IS A COMBINACION EN C++/ANOTHER LENGUAGE IN THE FOURTH PANEL ASSERT HAS NOT PARENTHESES. IN C++ THE ASSERT MUST HAVE THE PARENTHESES AND SO CANNOT BE A C++ PROGRAM. PLEASE ADVISE {{unsigned ip|108.162.210.219}}
:::I think he meant it as c++. Higher level languages that forego the parens tend to also forego the semicolon. Probably just a typo on Randall's part since he had recently learned Python relative to this. {{unsigned|Flewk}}

man this one made me cry...

if i could at least forget what happened to sally...
i wish it was as easy as "del filename".

this one, sadly, is too relatable for me. [[User:An user who has no account yet|An user who has no account yet]] ([[User talk:An user who has no account yet|talk]]) 15:56, 5 September 2023 (UTC)

Isn't this black hat, rather than cueball? But following on from two comics earlier? {{unsigned ip|162.158.216.190|18:51, 1 June 2025}}
:Hatless Black Hat has visible hair... [[Special:Contributions/162.158.33.240|162.158.33.240]] 21:53, 1 June 2025 (UTC)

Talk:3090: Sail Physics

2025-05-17T18:29:36Z

162.158.33.240:

After the last step, the sailors would then need to ground the boat to avoid being pushed in a circle, wouldn't they? [[User:Sophon|Sophon]] ([[User talk:Sophon|talk]]) 20:47, 16 May 2025 (UTC)

Note that for eastward wind, the boat will be propelled upwards, while the opposite is true for westward winds. This provides a basis for the functioning of airships and planes (Helicopters are more complicated, and additionally rely on their own magnetic fields) [[Special:Contributions/162.158.217.45|162.158.217.45]] 21:21, 16 May 2025 (UTC)
: Hence why you should always touch an earthing rod before approaching a helicopter, to avoid the magnetism pulling you into their rotors. [[User:Kev|Kev]] ([[User talk:Kev|talk]]) 03:11, 17 May 2025 (UTC)

Is this actually wrong? Wouldn't it still be ''a'' force on a sailboat, even if it's not the strongest? [[User:Smurfton|Smurfton]] ([[User talk:Smurfton|talk]]) 22:20, 16 May 2025 (UTC)

: I added some explaination on direction and magnitude of the lorentz force, maybe that will help - sga {{unsigned ip|172.68.234.227|22:33, 16 May 2025 (UTC)}}

The explanation states that of the four forces, only the electromagnetic force operates at the macro level. This is incorrect, as gravity is also directly observable by humans. There should also probably be a link to https://en.wikipedia.org/wiki/Airfoil to provide an explanation for how sails actually allow a boat to sail upwind. I recommend removing the remark about the poles potentially flipping in the future, as this is irrelevant. [[Special:Contributions/172.68.55.124|172.68.55.124]] 23:52, 16 May 2025 (UTC)

: What i meant was, for 2 objects at scales of humans =, maybe did not prase it well. In this case, it is the wind and the sail. Wind does not have a "mass" (the atoms most certainly do, but) we essentially have a pressure force, or momentum of wind, where instead of using the energy of atoms (and hence the mass) as given by kinetic theory is not used (that is random (as given by boltzman maxwell statistics)) and uniform (in the sense that for any direction, number of particles going against and towards is equal) and what we have is just pressure applied by a effective "group velocity" of the wind atoms. The gravity interaction between wind and boat, or the local waves and boat is negligible, and planetary gravity is not considered because that is not relavant for in plane motion. the pole fillping was added just for future proofing the article. I am sorry for the puns. I have rewwritten some parts, and reduced the part about pole flipping, and also added the average case scenario for the force, hope it is better now. - sga {{unsigned ip|172.70.143.75|02:37+, 17 May 2025}}
::That is one huge rambling paragraph, if it's (mostly) yours. I'm no stranger to ''writing'' huge rambling paragraphs, myself, but I gave up only a little way in on trying to make it read better. Grammatically, prosaically and with relevence.
::May I suggest that each 'frame' is treated to its own (shorter) paragraph, explaining what effect it tries to convey, what logic it individually tries to follow, but where it fails and what actual forces dominate a true example. (e.g. the hull-shape, including keel, helping convert roughly lateral sideways forces into forward ones against the water; those lateral ones having already been a conversion of largely head-on winds in the first place, thus two "almost up to 90 degree" redirections of force allow ''very nearly'' a 180-degree reversal of wind-blown movement. Feel free to discuss the comparisons and differences between 'flappy sail', though blown taught by the air, and an 'upright aircraft wing' solid design. ...See, told you I could ramble, but someone can surely do better at segmenting and summarising the basics of this.) [[Special:Contributions/172.71.178.32|172.71.178.32]] 08:32, 17 May 2025 (UTC)

This is super embarrassing to admit, but I came here to verify whether this was a serious thing or not. I had no idea how a sailboat sails against the wind. [[User:Catgofire|Catgofire]] ([[User talk:Catgofire|talk]]) 23:58, 16 May 2025 (UTC)
:You aren't alone - I think I was an adult before I understood tacking in the sailboat sense of the word. [[Special:Contributions/162.158.174.127|162.158.174.127]] 02:45, 17 May 2025 (UTC)
: I'm wanting to add in some wisdom about "science-y" explanations that appear to be sensible but are completely wrong, segueing into how generative language models appear to be far more reliable than they are. However this margin is too narrow [[User:Kev|Kev]] ([[User talk:Kev|talk]]) 03:09, 17 May 2025 (UTC)

I've been really annoyed with ExplainXKCD in the last few months ever since the initial posting has always been LLM generated. It requires more brain power to make sense of AI slop and edit it, than to contribute to a blank page. [[Special:Contributions/162.158.162.103|162.158.162.103]] {{unsigned ip|162.158.162.103|15:44, 17 May 2025|...yes, probably signed with just three tildes, by accident, but the intended message is the same...}}
:I don't think that LLM has been used for the most troublesome bits. LLMs can 'hallucinate', but tend (unless ''specifically'' asked) to make a lot more grammatical sense if you don't look too much further. [[Special:Contributions/162.158.33.240|162.158.33.240]] 18:29, 17 May 2025 (UTC)

Any chance we can add an explanation of how it *actually* works? [[Special:Contributions/162.158.216.174|162.158.216.174]] 10:03, 17 May 2025 (UTC)
:Through judicious angling of sail, wind (from any direction other than fully head-on) is deflected(/uses 'wing-effect') to create a force, trying to push the boat, that might be mostly sideways but also a bit forward. Because of the shape of the hull, any sideways force is resisted by the water, reinforcing the remaining forward component which the hull is far more ready to take advantage of. Enough sail (and enough stability to resist rolling) gives a large amount of movement towards, but not ''exactly'' towards, the wind. [[Special:Contributions/172.69.224.72|172.69.224.72]] 10:41, 17 May 2025 (UTC)

The joke is that the most commonly used explanation for why flow over a foil generates lift - particles going one way have a longer way to travel than the other, which generates a difference in speed and therefore a pressure differential - is wrong. {{unsigned ip|172.69.109.91|10:36, 17 May 2025}}

The picture seems to show an axis of rotation (the mast) for the sail being on the end of the sail. Is that correct for a certain class of sailing vessel?~~ {{unsigned ip|162.158.146.128|15:57, 17 May 2025}}

Talk:3090: Sail Physics

2025-05-17T08:15:04Z

162.158.33.240: sorry not sorry