Wikipedia:Reference desk/Archives/Science/2020 November 30

Welcome to the Wikipedia Science Reference Desk Archives
The page you are currently viewing is a transcluded archive page. While you can leave answers for any questions shown below, please ask new questions on one of the current reference desk pages.

November 30

What sort of elk was Horace, the Carleton Elk?

Is the Carleton Elk Alces alces or Cervus canadensis? It looks like Alces alces to me, but I'm not a ruminantologist. Thank you, DuncanHill (talk) 04:26, 30 November 2020 (UTC)

At least one source states, "By his palmate antlers he can be identified immediately as alces alces – a Eurasian Elk."^[1]  --Lambiam 12:48, 30 November 2020 (UTC)

Yes, bit of a long swim from Canada to Lancashire, whereas the linked article says that it was possible to walk from continental Europe at that time. Alansplodge (talk) 13:17, 30 November 2020 (UTC)

Many thanks, DuncanHill (talk) 21:09, 30 November 2020 (UTC)

Fuel consumption

In the US, fuel efficiency is typically expressed in miles per gallon. That is, how far can you on a given unit of gasoline. In Canada, the units are different, of course, but they're also inverted and modified, so that if you check fuel efficiencies while shopping for a new car you'll see it expressed in terms of litres per 100 km (example). That is, how much fuel will the car require to drive 100 km. Even though I'm Canadian born and raised, this has always seemed odd to me, both in terms of the inversion and the resulting modification by a factor of 100 to prevent talking in decimals. How did L/100KM come to be the standard? Is it only the standard in Canada or do other metric countries also use it? Matt Deres (talk) 16:33, 30 November 2020 (UTC)

In the UK we are "metric-in-name-only" on this. We buy fuel in litres but mostly describe fuel efficiency in mpg. As a result, websites such as "this one". are quite useful as they allow conversion between mpg and litres per 100 km. And that's UK gallons, of course, not US ones! Mike Turnbull (talk) 17:21, 30 November 2020 (UTC)

Fuel has been sold in litres in the UK since 1995 [2] but road signs are still in miles, so it's a right old muddle. Alansplodge (talk) 19:30, 30 November 2020 (UTC)

Isn't it more helpful to know how many liters per 100km than the other powers of ten or how far you can joyride on a liter or gallon? Sagittarian Milky Way (talk) 17:31, 30 November 2020 (UTC)

(ec ) It is also common in Germany.^[3] In the UK, although officially metric, MPG is the commonly used unit.^[4] In France they prefer to tell you how economical a car is in €/km,^[5][6] but if they cite a quantity for the fuel efficiency, the unit is also L/100km.^[7] The dimension of this unit is area. Imagine a gasoline-filled channel parallel to the road from which the car, as it goes along, scoops up a cross section of precisely that area.  --Lambiam 17:34, 30 November 2020 (UTC)

It's not only common in Germany, it's the standard by which fuel economy is expressed and marketed. I think this holds over most of (EU-)Europe. --Stephan Schulz (talk) 22:26, 30 November 2020 (UTC)

On the TV show "Top Gear" they always talked in terms of miles per hour and such. And on the BBC series "Escape to the Country", you'd never know the metric system even exists, as they always talk about acres and miles. ←Baseball Bugs ^{What's up, Doc?} carrots→ 22:02, 30 November 2020 (UTC)

We still officially use Imperial measures for speed, distance, and height on roads (and pints for milk and beer). I think everything else is officially metric, but unofficially many people still use Imperial (even those born after metrication) - and its not uncommon for people to mix systems. Iapetus (talk) 10:41, 1 December 2020 (UTC)

The Imperial acre was banned by the EU as a legal unit in 2010, but is still widely used conversationally. European Union abolishes the British acre Alansplodge (talk) 13:34, 1 December 2020 (UTC)

I will just note although the SI standard lists the liter as a unit "accepted for use" with the SI, nothing in the standard allows a unit to be formed with a denominator of "100 km". So any place that uses "L/100 km" is, to that extent, not conforming to the SI. --174.95.161.129 (talk) 00:07, 1 December 2020 (UTC)

• In France, car efficiency is expressed in L/100km. (Lambiam's second link defines a car use cost in €/km that does not only take into account fuel, but also car maintenance, and is definitely less well-know than €/km).

To address a minor point in the original post: presumably, the unit is L/100km rather than L/km so that the values fall in a reasonable range (between 1 and 20 for most small vehicles and conditions, instead of between 0.01 and 0.2 for L/km). Tigraan^{Click here to contact me} 08:55, 1 December 2020 (UTC)

Er, yeah. I mentioned that. To my mind, that should have been a clue that they had the numerator and denominator wrong from the beginning. :-) Matt Deres (talk) 18:49, 1 December 2020 (UTC)

L/100km is the standard in Australia. [8][9][10] Mitch Ames (talk) 12:29, 1 December 2020 (UTC)

Identify Cantharidae (Coleoptera) from photo

A new contributor uploaded this nice macro photo of an insect, saying they are from the family Cantharidae. It's a decent photo, so it would be nice to categorize it to a species if possible. Can you tell the species from the photo and the uploader's media description? I don't know any more details than what's in the descriptions, because I'm not the uploader. But the description does give a location and other useful info. I don't speak Ukranian so I don't understand the Ukranian description: it may contain a vernacular name that identifes the species. – b_jonas 20:15, 30 November 2020 (UTC)

• 
  the soft beetles in question
• 
  Cantharis fusca mating
• Cantharis fusca mating

They look much like the beetles (Cantharis fusca) also getting it on above in the two rightmost boxes.  --Lambiam 23:31, 30 November 2020 (UTC)

Different antennae, red vs black femurs; not the same. Abductive (reasoning) 02:21, 1 December 2020 (UTC)

Cantharis rustica looks a more likely match, although the female in the image seems to lack the dark blotch on its pronotum. The distribution fits, and other sources suggest it's fairly common. PaleCloudedWhite (talk) 12:25, 1 December 2020 (UTC)

Thanks for the help so far. – b_jonas 11:34, 3 December 2020 (UTC)