Science desk
< February 2	<< Jan \| February \| Mar >>	February 4 >

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.

February 3[edit]

Antique car terms[edit]

What does of opposed 6x4 ins cylinders far in front crosswise side chains to rear drivers on page 225 of 1906 Automobile Trade Journal, Volume 10 mean? --Doug Coldwell (talk) 11:04, 3 February 2022 (UTC)[reply]

It seems to be describing part of the Lambert friction gearing disk drive transmission, which used chains as the final part of the transmission. There are several articles relevant to these early cars/trucks, for example Lambert Automobile Company and Buckeye gasoline buggy. Mike Turnbull (talk) 12:30, 3 February 2022 (UTC)[reply]

Interested specifically in what 6x4 ins cylinders means.--Doug Coldwell (talk) 15:41, 3 February 2022 (UTC)[reply]

The reference you cite says: "and has cylinders of 6x4½ ins.," – this is the bore × stroke so the cylinders were 6 in (150 mm) in diameter with a stroke length of 4.5 in (110 mm) giving a total displacement of 127 cu in (2,080 cm³) Martin of Sheffield (talk) 16:30, 3 February 2022 (UTC)[reply]

To make the math more explicit, the volume of a cylinder is πr²h, so that's 3.14 * 3 in * 3 in * 4.5 in = 127 in³ --Jayron 32 16:42, 3 February 2022 (UTC)[reply]

Yes, but possibly better expressed when the bore is given as π(D⁄2)²h or possibly even π(B⁄2)²S Martin of Sheffield (talk) 17:03, 3 February 2022 (UTC)[reply]

Indeed and more accurately so, because π is not equal to 3.14. Philvoids (talk) 17:57, 3 February 2022 (UTC)[reply]

and 6 inch is not 150 mm but 152.4 mm, and 3.14 × 3 in × 3 in × 4.5 in is not 127 in³ but 127.17 in³, and 127 in³ is not 2,080 cm³ but 2,081.157128 cm³. Tsk tsk, what is the Reference desk coming to... --Lambiam 21:24, 3 February 2022 (UTC)[reply]

The endless decimal places of numbers like Pi are misleading. 3.14 is implicitly 3.1400, while 3.1416 is closer to the actual value of Pi. But the difference between the two numbers is only 1.6 one-thousandths. --←Baseball Bugs ^{What's up, Doc?} carrots→ 21:35, 3 February 2022 (UTC)[reply]

Unless anyone can tell me to what accuracy the original cylinders were made in 1906, I'd guess that 2 sf is reasonable. Anyhow, O-level maths taught us that your 3.1416 isn't accurate, the figure we learnt was 3.14159. Kids today! They never learn like we used to in the old days. :-) Martin of Sheffield (talk) 22:45, 3 February 2022 (UTC)[reply]

To one less trusting than BB above, 3.14 to me implies only ( >3.135 AND <3.145 ). I am assured that π is somewhere in that range but it's not easy to pin down. Philvoids (talk) 11:03, 4 February 2022 (UTC)[reply]

Useing 3.14 and 3.1415926535897932384626433832795028841971693993751058209749445923078164062862089986280348253421170679821480865132823066470938446095505822317253594081284811174502841027019385211055596446229489549303819644288109756659334461284756482337867831652712019091456485669234603486104543266482133936072602491412737245870066063155881748815209209628292540917153643678925903600113305305488204665213841469519415116094330572703657595919530921861173819326117931051185480744623799627495673518857527248912279381830119491298336733624406566430860213949463952247371907021798609437027705392171762931767523846748184676694051320005681271452635608277857713427577896091736371787214684409012249534301465495853710507922796892589235420199561121290219608640344181598136297747713099605187072113499999983729780499510597317328160963185950244594553469083026425223082533446850352619311881710100031378387528865875332083814206171776691473035982534904287554687311595628638823537875937519577818577805321712268066130019278766111959092164201989 both give the answer as 127 in³ when rounding to the whole cubic inch, which seems reasonable given the precision of the measurements (it's actually TOO precise, as the diameter is given as 6 inches, and not 6.00 inches; at 1 significant digit, anything more precise than 100 cubic inches represents a false precision). But anyone who actually knows how to do math would have known that already and not tried to feed extra digits of pi into their calculator that will just get rounded off in the final answer anyways. --Jayron 32 12:05, 4 February 2022 (UTC)[reply]

Although the discussion is about an American truck, 3.14 was a standard recognised approximation to π in Germany for many years. I suspect that in 1906 very few people had calculating machines, a simple division like 22/7 (3.142857) has always done me fine for rough calculations. Maybach apparently used 355÷113 (3.1415929203539823008849557522124) in their tank engine manuals before and during WW2. 'Opposed cylinders' probably means a flat or boxer engine. MinorProphet (talk) 10:01, 10 February 2022 (UTC)[reply]

Grey-on-white texts[edit]

Some websites routinely display text as dark grey (such as #262626) on a white background. I find this harder to read, and especially so when the font is thin (such as Roboto), and wish I could turn this off. Question: is there some known reason for this presentation style? --Lambiam 12:21, 3 February 2022 (UTC)[reply]

The reason is likely that the people who do this are bad at design? --Jayron 32 12:52, 3 February 2022 (UTC)[reply]

Who does the website design, and for whom? Typically someone with an artistic flair is contracted to create a website for a customer. They are not contracted to produce a website for the readers, if it looks good then they get paid. The requirement is that the website stands out from the competitors and has all the latest "snazzy" tricks. Martin of Sheffield (talk) 13:42, 3 February 2022 (UTC)[reply]

Can you link an example? --←Baseball Bugs ^{What's up, Doc?} carrots→ 14:20, 3 February 2022 (UTC)[reply]

Here are two examples: UScourts.gov (maintained by the Administrative Office of the US Courts on behalf of the Federal Judiciary – no competitor) and Scientific American, which is even grey-on-grey, a form of torture (likely an in-house job; their "Senior Web Producer"?). There was a pre-Internet period when brown-on-yellow textbooks were in vogue under the theory (if I recall correctly) that the lesser contrast in intensity reduced eye strain. --Lambiam 14:46, 3 February 2022 (UTC)[reply]

As a child mentally digesting Children's Digest that for many years was printed on light green paper, which the pubisher claimed avoided eye strain while reading, I concluded only that it was published on the cheapest possible unbleached pulp paper. Philvoids (talk) 17:52, 3 February 2022 (UTC)[reply]

But see Irlen syndrome (probably not a thing, but coloured overlays are often used to treat dyslexia). Alansplodge (talk) 21:55, 3 February 2022 (UTC)[reply]

From a design POV, using dark grey text and/or a pale grey background can make the images 'pop', with the shadows looking deeper and the highlights brighter. I'm not aware of any research but I personally find the main cause of eyestrain to be harsh white backgrounds. nagualdesign 00:16, 11 February 2022 (UTC)[reply]

Phase of ammonia at NH3 at 10bar[edit]

What's the boiling temperature of ammonia at 10bar? I've seen numerous calculators and equations but they are all in disagreement with each other. JoJo Eumerus mobile (main talk) 20:23, 3 February 2022 (UTC)[reply]

According to this it is 298 K. Ruslik_Zero 20:39, 3 February 2022 (UTC)[reply]

Ammonia is one of those common chemicals where Wikipedia has a good data page with this and other information. Note that there is a big difference between concentrated aqueous ammonia ("880 ammonia", as often purchased) and the pure material that you presumably are interested in, Jo-Jo Eumerus Mike Turnbull (talk) 22:11, 3 February 2022 (UTC)[reply]