Wikipedia:Reference desk/Archives/Science/2020 January 1

= January 1 =

Classic car
Is 20 years supposed to mean or symbolise anything. How do classic cars become 20 years it obviously has to have the historical importance with it but what is 20 years?? — Preceding unsigned comment added by 2001:8003:7427:6B00:B0F5:766D:B6BF:DEBF (talk) 02:28, 1 January 2020 (UTC)


 * Your question is not fully clear to me. Maybe you live in an area where being 20 years old allows a car to be classified as a classic car. Perhaps a look at our Classic car article will help clarify things a bit for you. (For starters, the definition varies widely around the world. ) HiLo48 (talk) 02:35, 1 January 2020 (UTC)


 * Are you the same user who kept coming here to enquire again and again about what makes classic literature classic? That got old quickly. Matt Deres (talk) 04:01, 1 January 2020 (UTC)
 * You mean it got "classic" quickly? --Trovatore (talk) 21:13, 1 January 2020 (UTC)
 * It's a rule of thumb. They're going by decades and saying a car generally has to be at least two decades old before it can start to be considered "classic". They're not saying all cars become "classic" the moment they become twenty years old. They presumably judged one decade as being not long enough, and three decades as too long for some examples. --47.146.63.87 (talk) 09:36, 1 January 2020 (UTC)
 * Here in Croatia you can request special classic car plates for cars older than 30 years. Other criteria are that you can't drive that car more than X days a week and you need to have other non-classic cars registered in your name and some other stuff. Probably so that people don't apply their crapola they use to commute just to get the discount on insurance and registration. 93.136.45.119 (talk) 19:59, 1 January 2020 (UTC)
 * In the UK, the tax people (HMRC) define a classic car as more than 15 years old for "benefit in kind" taxation of company cars. Insurance companies might offer "classic car insurance" on even newer vehicles, depending on type.  Alansplodge (talk) 21:54, 1 January 2020 (UTC)
 * In California it's 25 years for "classic auto" plates, though you can also order the (ugly) 1960s-style plates for any vehicle. --47.146.63.87 (talk) 10:50, 2 January 2020 (UTC)


 * There's two things at play here:
 * 1) The general meaning of "classic" is "kinda old, and kinda well liked" That's about it.  It's a very imprecise definition, but it is what people mean in common speech when they say something is "classic".
 * 2) There are legal and other considerations for which an imprecise definition is bad. For example, some state taxation policies may have special taxation rates on "classic" cars.  They obviously need to define some time limit on what that agency means by "classic" for their policies.  Those definitions are set by those agencies for only that specific purpose, thus times like "20 years" or "25 years" or some such are only defined for the specific purpose they are used for, and not meant to be generally applicable to ANY other situation.  For other situations, the imprecise common definition is usually meant.
 * I hope that helps. -- Jayron 32 16:20, 2 January 2020 (UTC)
 * There's also the "instant classic." I despise the term, but it refers to something that is instantly a classic because enough people assume that it will certainly be classic once it is old enough. When the PT Cruiser came out, it was referred to as an instant classic because it was unique. Now that it is getting 20 years old, I personally don't know of anyone that considers it a classic car. 168.149.143.112 (talk) 17:36, 2 January 2020 (UTC)
 * That's typically marketing hype and means nothing. If the PT was so great, why did they stop making it? Old, of course, is not a ticket to being "classic". I doubt anyone with an ounce of reality would call stuff like the Pinto or the Pacer "classic". ←Baseball Bugs What's up, Doc? carrots→ 23:19, 2 January 2020 (UTC)

Is cotton candy flammable?
I have cotton candy and matches, but I'd rather not perform the experiment myself. Temerarius (talk) 20:42, 1 January 2020 (UTC)
 * Given that it's nearly pure sugar, a relatively simple carbohydrate which is essentially a hydrocarbon with some oxygen included, and is in a quite finely divided form (see the Sugar article's Subsection Sugar), I'm pretty sure that it is not only flammable, but vigorously so. The fact that our Glucose article has a section entitled "Rocket fuel" is also suggestive. I have never tried the experiment (and indeed have not consumed any of the stuff — known in the UK as Candyfloss – for around half a century), but I'll be astonished if there aren't videos of such an experiment somewhere on Popular Video-sharing sites. Good hunting. {The poster formerly known as 87.81.230.195} 90.204.182.54 (talk) 23:33, 1 January 2020 (UTC)
 * In this video the Cotton candy merely melts in a flame. DroneB (talk) 02:30, 2 January 2020 (UTC)
 * It's a question of geometry; the more surface area exposed, the more rapidly oxygen can react with the sugar. Various cotton candy mixes may have other ingredients—thickeners, emulsifiers, etc.—which will also affect their properties. As a fine powder, sugar and many other organic substances are dangerously flammable in large amounts; see dust explosion. --47.146.63.87 (talk) 03:56, 2 January 2020 (UTC)
 * In the video DroneB links, and others I have now seen, the "cotton candy" used seems somewhat more substantial than the "candyfloss" sort I had envisaged (as shown in the article's infobox). The name seems to cover a range of consistencies, so Temerarius might need to specify which sort they meant.
 * I note that the melting point of, for example, glucose approaches 150°C, and its heat capacity is nearly 3 times that of water, so getting molten sugar on one's skin is definitely something to be avoided. {The poster formerly known as 87.81.230.195} 90.204.182.54 (talk) 04:29, 2 January 2020 (UTC)
 * No, it gloms together instead of outgassing enough to sustain combustion. It will burn if you douse it in alcohol though. EllenCT (talk) 04:11, 2 January 2020 (UTC)


 * I used to participate in an educational chemistry magic-show for kids - we did a variation on the theme of the carbon snake that we called "elephant's toothpaste." Our version used sugar and sulfuric acid.
 * This was a form of rapid-oxidation of sugar (really, the correct term is "dehydration reaction", which is chemically distinct from ordinary burning); but it's highly exothermic and with the right set of circumstances, it could be explosive; and it would surely work with cotton-candy.
 * All the usual caveats apply: don't try the experiment without appropriate protective equipment, ventilation, training, and so on. Concentrated acid is hazardous for all sorts of reasons.  Also be careful of variations on this demonstration that use other chemicals - some release some pretty noxious and deadly toxic gases.
 * Nimur (talk) 16:42, 2 January 2020 (UTC)
 * We also have a Elephant's toothpaste article, but that demo is quite different than the sugar-dehydration concept. DMacks (talk) 00:01, 3 January 2020 (UTC)
 * Quite right - we may actually have used the hydrogen peroxide decomposition for "elephant's toothpaste" - I may be mixing up our stage-names and chemical-reactions. The key objective for selecting chemical reactions was to look cool for an audience of seven-year-olds; and a secondary objective was to select reactions that would evoke safe gases that wouldn't interfere harmfully with said audience.
 * Thanks for the link! Nimur (talk) 16:56, 3 January 2020 (UTC)