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

= April 5 =

What kind of psychometric test is this?
I’ve taken this exam as a requirement for a job. Unfortunately, I forgot what the exam was called. All I can remember is that the exam has 100 items grouped into five or four. Each group of five or four questions contains numerical, logical, and vocabulary questions. The questions look something like this: Something that you use when raining --- U, S,  G,  C,  M   (Umbrella)

A small explosive thrown by hand --- G, C,  W,  J,  Z    (Grenade)

An apple costs $2.50. If you have $10, how many can you buy? --- 4, 5,  6,  4.5,  5.5

Complete the series: 1, 2, 4, 7, 11, 16, ? ---                      22,  21,  20,  23,  24

What kind of psychometric test is this?49.144.142.130 (talk) 02:18, 5 April 2015 (UTC)


 * It reminds me of the IPATO, which was a special proprietary example of an aptitude test (more specifically - an intelligence quotient test), although the IPATO typically presented its answers in two-dimensional format just to slow certain thought-processes (and to favor people who were really good at linear algebra). Were these questions timed?
 * Proper administration of an intelligence test (like a Wechsler Adult Intelligence Scale test) typically costs a few hundred dollars. Fees cover the cost of the psychologists and professionals who design the test, as well as the intellectual property licenses for the questions and the scoring matrix - not to mention overhead costs to ensure sterile testing conditions.  Many similar IQ tests like the Scholastic Aptitude Test and the Graduate Record Examination are administered by private-sector companies and also generally cost over a few hundred dollars.  There are hundreds of alternative psychometric tests of similar caliber, vetted by individual contract companies or even built up by specialized in-house HR departments at large companies, that can be administered at much lower total cost.  Perhaps your test was one such proprietary company test.  Generally, such tests are not called "IQ" tests, for reasons of political correctness and avoiding liability, avoiding licensing, and avoiding strong emotional responses.  Without exception, such tests are named "Incoming Applicant Aptitude Scoring System" or some similarly verbose description; this serves to obfuscate intent, but only for the subliterate.
 * Nimur (talk) 03:36, 5 April 2015 (UTC)
 * For that first question, shelter, coat, gaiters, and a mackintosh are also valid answers MChesterMC (talk) — Preceding undated comment added 08:44, 7 April 2015 (UTC)

Air Pollution Maps
Are there any other detailed air pollution level maps like http://aqicn.org? I don't need real-time information like aqicn.org (though it would be nice), but I'm looking for one with the most data points. Aqicn.org only has a few per city unfortunately. WinterWall (talk) 09:18, 5 April 2015 (UTC)


 * No, there is no denser resource. There is satellite data but most of that is lower resolution and limited to long-term averages (plus it has large calibration issues).  There is also model data, but again lower resolution.  That said, why do you want more data points?  Most particulate pollution (the primary health concern) has a atmospheric lifetime of days and quickly becomes mixed on a regional scale (50-100 km).  Local effects, such as being next to a factory or highway tend to provide only moderate perturbations.  And, of course, some of the apparent detail is related to noisy or poorly calibrated instruments.  More important than where you live in the city, is where the air you were breathing came from over the last several days.  Air that is imported from industrial areas will usually be dirtier than that which can from agricultural or natural areas.  And that depends strongly on day-to-day (and even hour-to-hour) wind patterns.  Dragons flight (talk) 20:34, 5 April 2015 (UTC)

trees
Do trees grow as far down as they grow up? if you turned it upside down would it look the same? — Preceding unsigned comment added by Kelticone (talk • contribs) 11:53, 5 April 2015 (UTC)
 * It depends on the species of the tree, the distribution of water and minerals in soils (roots will grown towards them), and the wind load (wind encourages deeper roots). It is said of oak trees that the roots are about the same shape as the crown, but this http://gardening.stackexchange.com/questions/1555/how-far-on-average-do-tree-roots-extend-out-from-the-base-of-the-tree indicates otherwise. LongHairedFop (talk) 12:51, 5 April 2015 (UTC)


 * Oaks appear to oscillate. Roots gow, then stop, leaves and so on grow, then stop and go on with roots again. -- Hans Haase (有问题吗) 15:58, 5 April 2015 (UTC)


 * Most tree roots do not grow anywhere near as far down as the branches twigs and leaves grow up. The roots tend to spread out, often surprisingly shallowly in the case of conifers.  There are a few exceptions in species that are adapted to seeking deep water tables, but generally, for most species and most soils, the root pattern is wide but not very deep.  A Google search gives some patterns for different species.   D b f i r s   16:23, 5 April 2015 (UTC)


 * Yes, if you've ever seen a toppled tree, the roots tend to cover a circular area perhaps as wide as the crown, but nowhere near as deep. μηδείς (talk) 20:54, 5 April 2015 (UTC)

When looking at the Virginia department of Forestry you see that trees roots grow to the length the widest branch tips. From this we can see that the trees roots do not grow nearly the same length as the actual tree. You also see in they looked at the depth of roots for several different types of trees. By doing this they compared several different research papers to debunk a common myth about tree roots. They found that the deeper the roots the more drought resistant a tree is. And they only grow the length of the branch tips as well. For a final source I found that Jim Urban, FASLA, a noted tree and soil expert. He found that. “Roots require three things: water, oxygen, and soil compaction levels low enough (or with void spaces sufficiently large enough) to allow root penetration. If all these conditions are met, roots can grow to great depths. Under ideal soil and moisture conditions, roots have been observed to grow to more than 20 feet (6 meters) deep. From this we see that they have to have these for the tree to grow.” (Urban) Lami229 (talk) 21:40, 5 April 2015 (UTC)LaurenAlexis

Female sexuality
Are lesbian women more or less likely, statistically speaking, to be virgins after the age of 30 than their straight counterparts? Please provide citations to back up your data

Eyebubummerglue (talk) 18:05, 5 April 2015 (UTC)


 * Not an answer to the question, but as noted at virginity, not everyone used the same definition. Many heterosexual couples consider the loss of virginity to only occur when a penis penetrates a vagina, while homosexual couples often include oral sex, mutual masturbation, and other acts as a loss of virginity.  If one uses a definition that is tied to heterosexual acts, then it seems almost certain that many people who identify as homosexual are technically "virgins".  On the other hand, if you include a variety of other sex acts, then many people who have been "saving themselves" and self-identify as "virgins" would probably lose that status under an expanded definition.  Without a precise definition of which sex acts you mean, I doubt one could even begin to meaningfully answer the question.  Dragons flight (talk) 19:37, 5 April 2015 (UTC)


 * These two journal articles discuss the subjective nature of "virginity", and discuss some data that includes lesbian participants . SemanticMantis (talk) 19:31, 6 April 2015 (UTC)

Jet aerodynamics of sound
Jet aerodynamics of sound is it been save on the speed of light?--83.237.214.60 (talk) 20:26, 5 April 2015 (UTC)
 * I'm sorry, but this question is not understandable. Some of us can read languages other than English.  Therefore you may get a more useful response if you post your question in your native language. Short Brigade Harvester Boris (talk) 20:29, 5 April 2015 (UTC)

kettles in the bath
How many 1.5L kettles of boiling water would be needed to make a 80L bath of cold water the right temperature for bathing? — Preceding unsigned comment added by 108.192.136.193 (talk) 23:28, 5 April 2015 (UTC)


 * Anywhere from zero to many, depending on the temperature of the "cold" water and one's personal preference as to the right temperature for bathing. Short Brigade Harvester Boris (talk) 23:47, 5 April 2015 (UTC)


 * Many people use a bathing temperature of roughly 40 °C, so going with that if the cold water is 20 °C, the cold and boiling water should approximately be mixed in a 3:1 ratio. For a 80 liter bath this means 60 l of cold water with 20 l of boiling water (i.e. 13.33 kettles). Of course this is just an example of a typical situation; like the comment above points out, the answer can be quite different depending on the situation. - Lindert (talk) 00:09, 6 April 2015 (UTC)


 * (OR Alert) Having actually performed this experiment multiple times (after my gas-fired hot water system broke down), I can advise that in practice it takes rather more boiled kettles than the theoretical calculations indicate.
 * The problems are that (a) one has to boil the n kettles sequentially, not all at once, and (b) it takes several minutes for each kettle to boil, and all this time the hot water already added to the bath is cooling down. I started with a quantity of cold water already in the bath (to minimise the differential heat loss effect) and boiled two kettles in relay, switching on the next filled one before even pouring the previous one into the bath. To achieve a minimally useful depth of acceptably warm bath water took 30-40 minutes of this quite physically energetic process (depending on ambient temperature – it was winter). It also proved very expensive in terms of electricity bills – I ran up a deficit of several hundred pounds (sterling) which took me over a year to pay off.
 * If the OP is in a similar actual situation, I can advise a much easier and cheaper method which occurred to me eventually (being a dumb First-Worlder ). Boil one kettle of water and pour half of it into a basin by the bath (my handbasin actually overhangs my bath, which is ideal). Diluted with cold water to a comfortable temperature, this is ample to wet oneself down with a flannel while standing in the bath, soap and scrub, and perform one rinse. The second half, similarly cooled, then suffices for a second and definitive rinse.
 * One kettle's worth also proves ample for hair washing and rinsing with the aid of a pan while bent over the bath. I actually find this preferable to and more thorough than just lying in a bathful of water, though I admit the latter also has its attractions. It also steams up the bathroom much less, reducing any problems arising from condensation, like mould
 * In case anyone wants to raise the point: yes, installing a shower is in my long term plans. {The poster formerly known as 87.81.230.195) 2.218.13.204 (talk) 15:57, 6 April 2015 (UTC)


 * In the big drought of 1976 we where advised to "Save Water, Bath With A Friend" If your friend don't like cold water and has a job – problem solved. You might even get a free back scrub. --Aspro (talk) 21:30, 6 April 2015 (UTC)


 * The answer is that you need 80L of boiling water, then you let it cool to the temperature you like. I believe 's equation might be wrong; I think you have to convert to Kelvin first. μηδείς (talk) 02:07, 7 April 2015 (UTC)


 * No, it's the temperature differences that matter, not the absolute temperatures, so any units can be used, as long as they are used consistently. StuRat (talk) 02:25, 7 April 2015 (UTC)


 * Some points:


 * 1) If you have a helper, they can add kettles of hot water while you bathe. You can start bathing with a small amount of water, and continue bathing as that water cools and more hot water is added.  Of course, the helper has to be careful to add the water on the far end of the tub so as not to burn you.


 * 2) Bubble bath seems to help to keep the water warm, by providing an insulating blanket of foam.


 * 3) The room temperature also matters, both because the bathwater will cool faster in a cold room, and because it will feel colder, even the water is the same temperature. StuRat (talk) 02:30, 7 April 2015 (UTC)