Wikipedia:Reference desk/Archives/Science/2015 October 5

= October 5 =

Is this item from "Geek" safe to use?
Someone I know ordered this thing for me from "Geek" and I was curious if it's really safe to use. Their idea was that it would be helpful for when I use my phone's GPS navigation feature, but I question whether or not it's safe to attach something like that to the steering wheel considering there is an airbag in the steering wheel. It shipped directly from China, so the manufacturer may have dodged United States Consumer Product Safety Commission regulations. Thoughts? PCHS-NJROTC (Messages) Jesus Christ loves you!  02:50, 5 October 2015 (UTC)


 * Attaching anything to the wheel that could interfere with emergency steering (and this definitely looks like it could) is unwise. The airbag issue seals the deal. Shock Brigade Harvester Boris (talk) 03:37, 5 October 2015 (UTC)


 * It's fine to use when the vehicle is stationery, but in the UK it would probably be considered illegal to use it when driving, and, of course, it would be very difficult to use on curved roads. For navigation, I mount my phone just behind the steering wheel.    D b f i r s   08:39, 5 October 2015 (UTC)


 * There's a 2012 patent http://www.google.com/patents/US20120080465, looks pretty much the same. So probably a cheap copy (assuming the patent made it to market). No safety guarantees here... Ssscienccce  (talk) 15:28, 5 October 2015 (UTC)
 * It seems that now everybody wants to strap an iPhone or iPad to the controls! A wide variety of yoke mounts are available; here's an article from Sporty's (it's a little bit of a promotional piece, but it's brand-agnostic and very informative): Where should I mount my iPad in the cockpit?  My vehicle doesn't have a steering wheel or a yoke, so I prefer to strap my supplemental navigation electronics to my leg or on my clipboard; but I know a lot of folks who like to keep their head up.  Safety means many things: if a distraction from an electronic device is diminishing your safety, or if the device is interfering in any way with your control, don't use it; if a supplemental electronic information system helps you navigate, or reduces your workload, it can improve safety.
 * The original question asked whether such a device "dodged" some type of safety regulation. As far as I know, there is very little legislation or government regulation regarding such systems in automobiles; most states are very liberal in allowing owner modifications to the interior of the automobile cabin.  Specifically, automobiles are outside the jurisdiction of the Consumer Product Safety Commission (vehicles, including after-market modifications to vehicles, are regulated by the National Highway Traffic Safety Administration and the individual state governments; the regulations are incredibly non-specific, e.g. 49 C.F.R. §567.7   Requirements for persons who alter certified vehicles).  As far as airbags, there is some extra legal-ese regarding any alteration that can "make inoperative" the safety feature; if adding a steering-column-mounted electronic device "makes" the crash safety system "inoperative," the installer (not the manufacturer) would be in violation of Federal regulations.  In other words, you carry the liability, not the device vendor.
 * Some consumer groups may make independent, nonregulatory safety guidelines and publish them for manufacturers, in the spirit of safety and conservative judgement; but noncompliance would not be "dodging" any regulation.
 * As far as using such systems in an aircraft... some very conservative individuals may broadly construe strapping an iPad to a yoke as a "major alteration," and recommend the filing of paperwork; but they're probably not in the mainstream. To help you navigate this question, FAA published Advisory Circular 20-173 Installation of Electronic Flight Bag Components, which provides further references to regulations for crash safety.
 * Nimur (talk) 13:12, 6 October 2015 (UTC)
 * The main danger would seem to be in encouraging drivers to take their eyes off the road. AndrewWTaylor (talk) 11:43, 5 October 2015 (UTC)


 * There's little danger of interfering with the airbag, but I agree it could interfere with steering and distract the driver, so a bad idea for those reasons. StuRat (talk) 22:23, 5 October 2015 (UTC)

Paint color
What color floor paint do i need to add to black paint to get a dark brown color?--213.205.252.131 (talk) 03:27, 5 October 2015 (UTC)


 * Brown (or light brown, depending on the tone you want). Sometimes the obvious answer is correct. Shock Brigade Harvester Boris (talk) 03:38, 5 October 2015 (UTC)
 * Cant get brown other wise I would have bought some. Only get red, yelloe or lite browny.--213.205.252.131 (talk) 04:00, 5 October 2015 (UTC)
 * Well, according to our brown article, brown is a mix of Red and green. However, I suspect that if you have black paint, what you will find is that it is going to be VERY difficult to "dilute" the color, you will need a LOT more brown paint than black paint to make dark brown, I suspect sat least a 10:1 ratio, if not even more. Normally to get dark paint you would start with the color you want and add just a LITTLE black paint, probably even less than 10%. In my experience, black paint is very "strong", you only need a tiny amount to change the shade of another paint color quite considerably, and you can very quickly add 'too much' making the mixture very dark. I suspect that even if you have as much light brown paint as black paint, if you mix them together, the result will still be pretty much black. Vespine (talk) 04:44, 5 October 2015 (UTC)
 * Red plus black should give a shade of dark brown, but sometimes the actual results are significantly different from what colour theory would predict because paints are often not pure shades of their stated colour, so it is important that you try out a tiny sample first to make sure that you get the shade that you want before mixing large amounts.   D b f i r s   08:26, 5 October 2015 (UTC)


 * I agree with Vespine, adding paint to black is not the way to go, you'll end up paying more and with more paint you can't use. imho...  Ssscienccce  (talk) 00:27, 6 October 2015 (UTC)
 * So shall i get the lite brownie and add some black till i get the rite shade??--213.205.252.131 (talk) 01:54, 6 October 2015 (UTC)
 * How much paint are we talking about? Are you painting a picture or are you paining a whole fence? Can you do a trial first with just a small amount of paint to see what the result looks like? That would be your best bet otherwise you can ruin a lot of paint if you just start mixing it in bulk. Without seeing the paint and actually trying it, no one here will be able to confidently tell you if any trial you attempt will result in something you think is suitable shade of brown for whatever purpose you need it. Vespine (talk) 01:58, 6 October 2015 (UTC)
 * Well as i asked in my question about 'floor' paint, it is floor paint. So Im painting a ? ...... floor. Area 3 sq ft (approx) — Preceding unsigned comment added by 213.205.252.131 (talk) 02:06, 6 October 2015 (UTC)
 * Lol you did indeed, sorry, we call it "bloke blindness" :).. 3ft square is quite small for a floor, it really depends how important is it to you to get the color right. Any method you chose is going to involve a little trial and error. Vespine (talk) 02:41, 6 October 2015 (UTC)


 * The standard instruction is to make orange from red and yellow, then darken it to brown by adding black (or deep blue, with white to lighten it if necessary). If you first add red to black you will get maroon, which you can lighten with lots of yellow.  If you add black and yellow you will get an olive color that you can move towards brown by adding lots of red.


 * The olive and maroon routes are not advisable unless you have a lot of yellow and red to spare. The problem is that if you start with too much black, it is hard to lighten without adding a lot more red or yellow.  So the safe bet is the standard one: start with an orange made of half red and half yellow then slowly add black to darken. μηδείς (talk) 17:11, 6 October 2015 (UTC)
 * I can get the Ronseal terra cotta which is a bit like orange. If I mix that with black will that give dark brown?--213.205.252.131 (talk) 17:24, 7 October 2015 (UTC)
 * Where are you getting the paint? In the US one would normally go to the hardware store, get sample color cards, find the shade that most closely matched the desired color, go back to the store, and ask them to mix it.  I assumed from the above that you had a primary red and primary yellow available, as well as a lot of black.  In that case, making orange, then darkening it with black would be the normal procedure.  A little white or blue would halp if you found the brown was to darrk or red.
 * But it is impossible to give specific advice over the internet, because we don't see what you have and are not there as you mix it. Unless you are trying to restore an antique, what is the worst that could happen?  You'll just have to do trial and error.  But I will repeat that starting with an orange and adding black (terra cotta being a less saturated orange) is better than starting with a can of black and expecting to get to brown by diluting it. μηδείς (talk) 18:51, 7 October 2015 (UTC)
 * OK that's pretty useful advice. I shall try putting a bit of black into terra cotta. Thanks.--213.205.252.131 (talk) 23:15, 7 October 2015 (UTC)

What is the significance of 19 and a bit inches
This steel rule has diamond markings at multiples of just over $19 3/16$ inches. It is not a round value in millimetres either. They must serve some purpose as they are there along the whole length of the rule. The only thing I could think of was maybe something to do with 19-inch equipment racks but I can't think what. Probably not relevant, but there are also similar marks at exactly 16 inches. SpinningSpark 16:40, 5 October 2015 (UTC)
 * According to SDMB and this site, the markings are standard spacings for engineered lumber. The black marks are at 8/5 of a foot (19.2"). Tevildo (talk) 16:50, 5 October 2015 (UTC)
 * Right, these marks turn a standard measuring tape into a simple type of modular rule (I can't find our relevant page, see e.g. these products used in masonry ). The idea is to have the rule(r) marked in way so as to prevent a worker from having to mess around with mental modular arithmetic, and there is likely another marker at integer multiples of 19.2. SemanticMantis (talk) 17:09, 5 October 2015 (UTC)


 * The fifth one should be at exactly at the 8 foot mark, according to Tevildo's second link above. Alansplodge (talk) 18:49, 5 October 2015 (UTC)
 * (Yes, 5*19.2 inches = 96 inches = 8 feet :) SemanticMantis (talk) 19:06, 5 October 2015 (UTC)
 * Yes, there is a mark at exactly 8 ft. This is a multiple of 16" as well of course.  The same mark is used for both on this make of rule, but one of Tevildo's links above said that the 16" marks are in red to distinguish them. SpinningSpark 20:06, 5 October 2015 (UTC)
 * The 16" marks are likely intended for use with the nominal size of a standard 16" concrete masonry unit . SemanticMantis (talk) 19:04, 5 October 2015 (UTC)
 * I would've said they were likely intended for use with the standard spacing of wall studs. But of course what's likely (and for that matter what's standard) will depend on one's location. --174.88.134.156 (=talk) 04:45, 6 October 2015 (UTC)
 * Does the steel rule or its container display anything informational of a verbal or pictorial nature? Bus stop (talk) 13:08, 6 October 2015 (UTC)
 * See Tape_measure, although I dispute the placement of this information under "United States". Tape measures in the UK have these markings too. --Heron (talk) 18:09, 6 October 2015 (UTC)