Science desk
< April 17	<< Mar \| April \| May >>	April 19 >

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

April 18[edit]

Stupid question: What flowers are these?[edit]

[1] Thank you. 69.22.242.15 (talk) 00:36, 18 April 2017 (UTC)[reply]

Looks like cherry blossom to me. DuncanHill (talk) 00:38, 18 April 2017 (UTC)[reply]

Pretty sure that is a cherry blossom. Boomer Vial^{Holla! We gonna ball!} 00:46, 18 April 2017 (UTC)[reply]

Definitely cherry - and probably one of the Japanese varieties to get that deep pink. The image isn't clear enough to identify the variety. The only other tree which has similar bright pink blossom is the crab-apple - but that would have leaves as well as blossom. Wymspen (talk) 10:16, 18 April 2017 (UTC)[reply]

Indeed. Malus floribunda has similar flowers, but the leaves precede the blossoms by several weeks (or at least the one in my front yard does). With Prunus trees (plums, peaches, apricots, cherries, aka the Drupes) the flowers precede the leaves in spring. It's clearly a Prunus of some sort, "cherry blossom" is a possibility, but its hard to tell from that picture. Could be a peach blossom too, which also has similar pink flowers, or any of a number of plums, etc. which could have pink flowers. We'd probably need pictures of leaves and/or fruit to make a better ID. --Jayron 32 17:37, 18 April 2017 (UTC)[reply]

Ostrich wing span[edit]

I saw a cute commercial the other day of a very determined ostrich flying. How big would an ostrich's wingspan need to be for it to actually fly? 198.72.29.37 (talk) 18:44, 18 April 2017 (UTC)[reply]

This article has a handy graph which shows the wingspan/weight ratio for various birds. A simple linear regression can be done to extrapolate that data to the weight of a typical ostrich to figure that out. --Jayron 32 19:29, 18 April 2017 (UTC)[reply]

Very bizarre[2]. Is it real? --AboutFace 22 (talk) 19:30, 18 April 2017 (UTC)[reply]

If you mean have people filmed mature ostriches flying, no it is not true. That clip is currently being shown here in the UK as an advert for an electronics firm. I suspect the advert was created using CGI. DrChrissy ^(talk) 21:24, 18 April 2017 (UTC)[reply]

Jayron, thanks for finding that graph. I spent quite a bit of time looking for something similar but could not. Can you, or anyone else, please explain what that symbol before the 2 of the y-axis label means? DrChrissy ^(talk) 21:00, 18 April 2017 (UTC)[reply]

^2 means squared, to the power of two. It is used when the superscript is not possible. Wymspen (talk) 21:53, 18 April 2017 (UTC)[reply]

Right before "2" there is a caret "^" a symbol for the power. a^2 means a to the power of two. Is it what you want? --AboutFace 22 (talk) 21:54, 18 April 2017 (UTC)[reply]

Ah - that makes sense. Thanks very much. Using very rough figures then, the graph indicates the wingspan of a flying human is approximately 7 metres. Male ostriches can weigh almost as much as two humans, so if the linear regression can be extrapolated this far, flying ostriches would have a wingspan of approximately 14 m! I suggest we don't encourage them! DrChrissy ^(talk) 22:39, 18 April 2017 (UTC)[reply]

Just as a follow up, our article on the extinct Pelagornis sandersi states it is the largest flying bird discovered with a wingspan estimated to be between 6.1 and 7.4 m (20 and 24 ft). DrChrissy ^(talk) 22:56, 18 April 2017 (UTC)[reply]

As far as current birds, the great albatross is no slouch, with a wingspan up to 3.5 m. Also note that any attempt to figure out what wingspan an animal would need, based on it's weight, must also figure in the weight of those huge wings. StuRat (talk) 23:03, 18 April 2017 (UTC)[reply]

I think the additional weight of the wings would be a secondary consideration. The muscles required to fly would be massive and the keel bone (to which the flight muscles attach) would also need to be massive. DrChrissy ^(talk) 23:08, 18 April 2017 (UTC)[reply]

Yes, and then you'd need a bigger heart and lungs to provide oxygen for all that additional muscle, a stronger spine to support it all, etc. StuRat (talk) 02:15, 19 April 2017 (UTC)[reply]

Bird spines aren't particularly strong, see bird skeleton. To give a better lever arm, the flight muscles are anchored to the keel bone (an extended sternum) rather than to the spine. The pelvis can also be a large muscle attachment, depending on the species. It's generally the flightless birds that have the largest and strongest pelvis, and for some also the spine. The ostrich here is actually more solidly built (except for keel and wings) than a hypothetical flying ostrich. Andy Dingley (talk) 15:15, 19 April 2017 (UTC)[reply]

Birds (and all living things. Well, all things) are constrained by what is called the square-cube law. As wings grow in size, they grow in both weight and area; weight would be proportional to volume, which grows in three dimensions, while lifting force of a wing is related to surface area, which grows in two dimensions. That is, if you double the length of a wing (while keeping all other dimensions proportional), you increase its lifting force by a factor of 4 and its mass by a factor of 8. If you triple the length of a wing, you increase its lifting force by a factor of 9 and its mass by a factor of 27. This kind of scaling is why super large airplanes become hard to build; as the wings increase in size, they increase in mass faster than they increase in lifting power. The same would apply to the weight of bird wings. Larger birds have a greater proportion of their mass devoted to being wings. Compare humming bird to condor for example. --Jayron 32 14:52, 19 April 2017 (UTC)[reply]

A difference is that airplanes are hollow, and the wall thickness isn't necessarily proportional to size. That is, an airplane 10x as long doesn't need to have a fuselage 10x as thick. Some birds, do, however, have hollow bones. As for airplane size restrictions, economics seems to limit the size of commercial planes. There aren't many routes that can support 1000 passenger planes, especially if they need to pay to lengthen the runways, modify the terminals, etc. StuRat (talk) 15:42, 19 April 2017 (UTC)[reply]

The article I already linked deals, in a small part, with square-cube law as it relates to airplane design. It's nice that you have ideas, but references beat ideas every day. ALso: "The effect of aircraft growth on empty weight [is based on] the square cube law... The actual wing structural weight fraction will increase with the size of the aircraft". I assume you're looking at a source for your statement? Since you found a source for your statement before you thought to make it, perhaps you can share it? --Jayron 32 16:14, 19 April 2017 (UTC)[reply]

That article states: "The square-cube law is based on many simplifying assumptions and has been defeated by the ingenuity of designers. Aircraft will not be scaled up according to geometric similarity...". Geometric similarity is making a plane that's 10x as long also have 10x the wall thickness. StuRat (talk) 02:12, 20 April 2017 (UTC)[reply]

So that's a no on sharing references then. You're so good at refusing to provide references you should consider not providing references as a career. You'd be the best in the world at it. --Jayron 32 02:10, 21 April 2017 (UTC)[reply]

I did provide a reference, which happens to be the same as yours. Did you want me to repeat the link for some reason ? You are so good at cherry-picking what you use from your refs that you can probably just save time and assume all your refs say the exact opposite of the point you are trying to make. StuRat (talk) 05:18, 21 April 2017 (UTC)[reply]

This reference (Ellington, C. P. "Limitations on animal flight performance." Journal of Experimental Biology 160, no. 1 (1991): 71-91.) states "...maximum size for flapping flight is often taken as 12-16 kg" DrChrissy ^(talk) 17:40, 19 April 2017 (UTC)[reply]
That makes sense for birds, I think the largest flying birds are the condors which tops out at 14 kilograms, and bustards which tops out at 18 kg, so in that range. List_of_largest_birds#Table_of_heaviest_living_birds are all flightless until we get to the Kori bustard. (the domestic turkey can hypothetically fly, and their wild cousins do, but farm raised turkeys are bred in such a way as to make flight impossible. [3] --Jayron 32 18:07, 19 April 2017 (UTC)[reply]
I'm not sure I can agree with all of this. I once worked on a research project on the behaviour of farmed turkeys. As youngsters, they can sort of fly. They like to do vertical takeoffs to land on elevated objects - including the researcher's head. As sub-adults (16-19 weeks of age), I have never seen one fly. I'm not sue what you mean they are bred in ways which make flight impossible. Here in the UK, turkeys are reared in vast sheds which are sometimes converted airport hangars. I don't see how these would prevent flight. It is also relevant that the slaughter weight of males is 18-20 kg, so if they are able to fly, they would possibly be the heaviest flying bird. They also continue to put on weight after this time if they are not slaughtered which would put them way beyond the limit suggested above. Sorry this is all OR. DrChrissy ^(talk) 18:37, 19 April 2017 (UTC)[reply]
"As sub-adults (16-19 weeks of age), I have never seen one fly." You just answered your own question with your own experience. I don't know why you think adult domestic turkeys are capable of flight. You said you've never seen one. I don't understand why you would say I was wrong, and then say you don't agree with me when you then immediately do. The Wikipedia article states the same thing you do. But, if you need more sources regarding the difference between domestic and wild turkeys: [4] It notes how wild turkeys can fly, but that domesticated turkeys do not because, and I quote, "Farmers prize turkeys that grow large breast and thigh muscles, because those are the most valuable parts in the poultry market. Over time, farmers have bred turkeys to have larger and larger breasts. A turkey breast gets stronger as it gets larger, but the animal’s power-to-mass ratio diminishes, so it can’t flap quickly enough to support sustained flight." Not only a statement which references breeding as why domestic turkeys do not fly as adults, but ALSO a reference to the square cube law as to WHY they cannot! --Jayron 32 18:49, 19 April 2017 (UTC)[reply]
Apologies Jayron. I should have read your posting more carefully. You said "the domestic turkey can hypothetically fly" (my emphasis) - I missed the rather vital word "hypothetically". As for the way which turkeys are bred preventing them from flying, I jumped to the incorrect conclusion you were referring to environmental conditions. I agree totally with the reason for their not being able to fly is intense artificial selection to increase the size of breast muscles. Apologies for the confusion. DrChrissy ^(talk) 19:04, 19 April 2017 (UTC)[reply]

Wheatgrass[edit]

Aside from the alcohol, what would be the difference(s) between wheatgrass juice and beer or malt liquor? ←Baseball Bugs ^{What's up, Doc?} carrots→ 19:08, 18 April 2017 (UTC)[reply]

From the article you already linked, the third sentence "Wheatgrass differs from wheat malt in that it is served freeze-dried or fresh, while wheat malt is convectively dried. Wheatgrass is allowed to grow longer than malt." Malt is the stuff that serves as feedstock for brewing. --Jayron 32 19:25, 18 April 2017 (UTC)[reply]

Let me be more specific: How does it taste compared with the other items? ←Baseball Bugs ^{What's up, Doc?} carrots→ 20:56, 18 April 2017 (UTC)[reply]

You... seek a plain-language description of the taste of wheatgrass, written to a standard that would qualify as an encyclopedic and scientific reference? Well, why don't we start at the main article on qualia and see where we end up?

Almost everything you will find on the web for wheatgrass is going to be a commercial vendor trying to sell it at you. There just aren't very many philosophers who write about the subjective character of experience and make specific reference to wheatgrass.

Here's a really nice organic farm that will sell wheatgrass to you, via mail-order: the Dynamic Greens Wheatgrass Juice from the Stem Family Farm. What does wheatgrass taste like? "Neutral and unfamiliar but not unpleasant," ... and so on.

...For a few bucks, you can just buy a cup of wheatgrass juice at almost any Jamba Juice in the United States... here's the store locator... the marketing-ese text calls the juice "flavorful," so that's about all you're going to get. Even if you think it's silly, you can try it anyway and laugh it off as a novelty experience; you might even enjoy it.

And if you don't want to drink it because it is green, here's the research paper you ought to read: Baeyens, Flavor-Flavor and Color-Flavor Conditioning in Humans (1990), on the Pavlovian cross-stimulus conditioning of rat- and human- response, relating color, flavor, and ... well, nuclear radiation, as it turns out. (I found these articles while reading Plato's encyclopedia article on Associationism during my search for encyclopedic articles about wheatgrass juice).

Nimur (talk) 21:29, 18 April 2017 (UTC)[reply]

I just wondered if it tasted like non-alcoholic beer or not. But thanks for the tip. I'll see if I can find someplace where I can get a small sample. And if I do, I'll report back here. :) ←Baseball Bugs ^{What's up, Doc?} carrots→ 21:42, 18 April 2017 (UTC)[reply]

It doesn't like beer, non-alcoholic or otherwise. It tastes like grass. Bastun^{Ėġáḍβáś₮ŭŃ!} 10:44, 20 April 2017 (UTC)[reply]