Wikipedia:Reference desk/Archives/Science/2022 January 1

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January 1

Body proportion

It is given in BWH measurement that it is expressed as circumference of circle (which means ellipse). So I want to know what is ratio of two diameters of this ellipse. Of course this ratio will be different for all 3 measurements. Also it will depend on person to person based on cup size etc. But what are those at an average. -- 2409:4043:4E82:106D:917E:C85D:86A5:17CB (talk) 10:23, 1 January 2022 (UTC)

The term "circumference" should not be understood here in its technical geometrical sense. The American Heritage Dictionary gives as secondary meanings: "The boundary line of an area or object" and "The length of such a line".^[1] Here it refers to the measurement as found by using a measuring tape. In mathematical terms, it is the length of the boundary of the convex hull of the shape of a cross section of the human body. The shape of that convex hull forms only very roughly an ellipse. Not only will the ratio of its minor to major axis vary wildly between individuals, but the averages will also depend on the age group and other population characteristics. If you must have a number, for a rough-and-ready guess for the all-out average I'd go with 4 : 5.  --Lambiam 14:53, 1 January 2022 (UTC)

[OP:] Thank you for answer. I was just wondering this question when I was sketching a female body. If say I want to make height as 5 feet (so I scale it to 5 inches on paper) and I want that BWH ratio as 36-24-36 (hourglass figure), So I was just thinking what should be length between left end to right end at these 3 points that I asked above. so I thought if I got ratio of diameters then I will use formula, circumference of ellipse = 2*pi*sqrt((R1^2+R2^2)/2), and will get radius value and then can make that drawing. I know this sounds stupid :) But now that you told that it is not ellipse then tell me what are those lengths that I want. -- 2409:4043:2B10:FE3B:70BC:AB06:5A07:E4F5 (talk) 17:14, 1 January 2022 (UTC)

Sorry, but there is no elementary function for the circumference of an ellipse in terms of the lengths of its semi-major and semi-minor axes; see Ellipse § Circumference.  --Lambiam 22:05, 1 January 2022 (UTC)

So is the formula that I wrote above, wrong? Was I taught wrong formula at school? -- 2409:4043:2B10:FE3B:9C71:27ED:72F6:7297 (talk) 05:22, 2 January 2022 (UTC)

I can't verify if you were taught this formula, but in any case, it is wrong. Set $R_{1}=1$ and let $R_{2}$ get very small. Then, as $R_{2}$ approaches $0,$, the formula approaches $\textstyle {2\pi {\sqrt {(1^{2}+0^{2})/2}}=\pi {\sqrt {2}}\approx 4.44288}\,.$ But the ellipse gets more and more like a pair of straight lines, each having length $2R_{1}=2,$ and the true circumference approaches $4.$  --Lambiam 10:52, 2 January 2022 (UTC)

I'm no specialist on female body ratios (sorry, I'm male and single, like your average Wikipedia editor), but I suggest that if you want to draw a body and want to know the ratios, just look at a number of photos, pick the ones you like, measure the ratios and calculate the average. There are even categories for photos of sparsely dressed women on Wikimedia Commons (because many editors are ... Well, you get it). Of course, there's some selection bias in those pictures. PiusImpavidus (talk) 19:03, 1 January 2022 (UTC)

By doing a Google Image search on "36-24-36" you'll find plenty of models. (Not this one.)  --Lambiam 21:30, 1 January 2022 (UTC)

OK thanks both of you. -- 2409:4043:2B10:FE3B:9C71:27ED:72F6:7297 (talk) 05:22, 2 January 2022 (UTC)

Does NPN transistor work only when circuit contain two voltage supplies and batteries?

This is the basic diagram of NPN transistor; Image

It has two voltage supplies and two batteries. Can it won't work if only one voltage and resistor present in the circuit? Rizosome (talk) 11:04, 1 January 2022 (UTC)

This is an amplifier circuit using an NPN transistor with one voltage supply and resistors. See Transistor#Transistor_as_an_amplifier for details. Philvoids (talk) 11:48, 1 January 2022 (UTC)

I got answer from this: This is an amplifier circuit using an NPN transistor with one voltage supply and resistors. Rizosome (talk) 13:17, 2 January 2022 (UTC)

Resolved

Snake Found

A long time ago, I am too old to remember when, I asked about a very long black snake seen near one of my rental cabins in the piedmonts of South Carolina. Last week, a renter ran over a very long black snake that appears to be the exact same as the one previously seen. It was just shy of eight feet long. I took it to Clemson to get it identified. It is an indigo snake. They are not normally found this far north, but the identification is certain. They are popular pets, so it is possible that this is a pet that got loose and didn't travel very far. I don't really have a question. I just wanted to give an answer to the question I asked previously as there was a lot of discussion about how long the snake actually was. My personal opinion is that because the cabin is only a few miles from Hollywild animal park, the snake likely escaped from there. Now that it is gone, I will go back to only warning the renters about rattlesnakes (who don't make noise here), copperheads, and moccasins, just in case they are not smart enough to leave snakes alone. It is nice to know that the huge snake was not a overgrown moccassin. 97.82.165.112 (talk) 17:22, 1 January 2022 (UTC)

The range of the Eastern Indigo Snake as seen here borders the South Carolinian part of the Piedmont. With temperatures rising, the ranges of cold-blooded reptiles may be expected to begin extending further North.  --Lambiam 21:17, 1 January 2022 (UTC)

I think you were looking at the map of the swampsnake. The indigo map is farther down in the page. It is coastal and rarely further north than Georgia. That's probably why it stayed near the cabin. Plenty of critters like to stay under it because it is semi-insulated to keep the pipes from freezing and the humans leave plenty of scraps around to eat. I've tried attracting owls and chipmunks, but I mainly just have snakes, spiders, and the occasional white squirrel. 97.82.165.112 (talk) 17:44, 2 January 2022 (UTC)

I was looking at the map with the legend "Eastern Indigo Snake (Drymarchon couperi)". The northmost point of the black area is less than 15 miles from Augusta, Georgia, which (at least according to the map in Piedmont (United States)) is at the border of the Piedmont in South Carolina.  --Lambiam 20:38, 2 January 2022 (UTC)

I see. "piedmonts" is not a scientific term. Locally, it refers to the low mountains along the North Carolina/South Carolina border. It is also referred to as the "upstate." Regardless, the herpetologist said that she never saw one so far north and that it was likely an escaped pet. The entire point was just to identify the snake and point out the actual length. 97.82.165.112 (talk) 15:23, 3 January 2022 (UTC)

"Piedmont" means "foot of the mountain(s)" and Piedmont links to a similar region in Italy. --←Baseball Bugs ^{What's up, Doc?} carrots→ 03:50, 4 January 2022 (UTC)