Wikipedia:Reference desk/Archives/Science/2018 September 30

= September 30 =

Pianos vs motor vehicles: moving parts
A dear friend of mine, who's a highly experienced piano teacher, has told me that a piano has more moving parts than a motor car. I wonder if this would depend on the type of piano and the type of car. Or maybe it's absolutely correct. Or maybe not. Can someone shed light on this for me? --  Jack of Oz   [pleasantries]  00:19, 30 September 2018 (UTC)
 * It could well be true. Start counting the moving parts in a typical car, and they might fall short of 88, or whatever the magic number would be. ←Baseball Bugs What's up, Doc? carrots→ 01:38, 30 September 2018 (UTC)
 * I can tell you it's way more than just the 88 keys. And I'm sure any car would have way more than 88 moving parts.  --   Jack of Oz   [pleasantries]  02:06, 30 September 2018 (UTC)
 * Have you asked your friend to "prove it"? Or might that be a sensitive issue? ←Baseball Bugs What's up, Doc? carrots→ 02:13, 30 September 2018 (UTC)
 * Do you count the cams on a cam shaft or the wheel weights on the wheel? Technically, every part on a car is a moving part if the car is moving, no??? ;) Wnt (talk) 01:59, 30 September 2018 (UTC)
 * A piano can also be moved via its wheels, but I'm not so sure the basic chassis of either a car or a piano would count as a "moving part". ←Baseball Bugs What's up, Doc? carrots→ 02:13, 30 September 2018 (UTC)


 * These items claim that a piano has about 12,000 while a car has about 10,000. Piano and ←Baseball Bugs What's up, Doc? carrots→ 02:16, 30 September 2018 (UTC)
 * Our piano article cites a promotional website from Steinway & Sons, a piano building firm of international repute. The source claims: "There are 12,116 individual parts that make up a Steinway grand piano."  This is not the same as 12,000 moving parts.
 * In any event, the number of parts - moving or otherwise - is a poor proxy for the mechanical complexity of a system. Not all moving parts are equal in complexity.
 * Personally, I find the non-moving part of the piano to exude more complexity: for example, the curved hardwood that forms the distinctive casing, or rim, of a grand piano commands a five-figure premium over the straight wall of an upright piano; and in both types of piano, the soundboard must be crafted in a manner that simultaneously satisfies strict engineering requirements and artful imprecision. As discussed in our article on piano acoustics, it is the inharmonicity of a piano - "not because of a lack of precision" - that give each instrument it timbre - and why it takes so much effort for electronic synthesizers to produce an authentic piano sound!
 * Nimur (talk) 03:24, 30 September 2018 (UTC)
 * Nobody mentioned complexity. Just numbers of moving parts.  --   Jack of Oz   [pleasantries]  03:43, 30 September 2018 (UTC)
 * ec with Nimur (had trouble tracking down the piano-article ref to verify) As a quick guesstimate, I count 15 moving parts in the action of a grand piano key, which gives 1320 total. That does not include the mechanism of shifting the set of hammers for the soft pedal, holding up all the dampers for the sustain pedal, etc. but those are likelySWAG only a few tens each for the whole instrument or at most a few extra per key. DMacks (talk) 03:54, 30 September 2018 (UTC)


 * Cars would generally be seen as having more, because the manufacturing processes used involve assembling together smaller parts. Consider a piano action vs. an engine cylinder. 88 keys, 11 parts in a piano action per key; 8 cylinders (or 4) - we can simplify this to "Does a car have more than 11 moving parts per cylinder?" Maybe 22 in Europe.  Now the parts of that action are largely wooden, with many separate holes drilled into a piece of wood for each lever. The levers are few, but complex. But the car has separate parts, each staying separate until assembled by a mechanic in a garage (I'm counting parts which would be separated during repair as being "separate parts"). We have as many parts as a piano action just for each engine valve on an OHV engine.  If you start counting balls in ball bearings, then it's far more. Andy Dingley (talk) 09:49, 30 September 2018 (UTC)


 * Small numbers of parts are replaced in routine car maintenance but a full restoration that considers all its parts happens only rarely, if ever, to a car or a piano. One cannot meaningfully compare counts of "moving parts" without an even-handed definition of what constitutes a moving part. Some extreme views are possible e.g.


 * Every separable part that moves relative to another separable part when the piano/car is taken into use. The count includes screws holding the piano lid to its hinge, and every ball in the car wheel bearings.


 * Literally every separable part because pianos and cars both have continual motions, both vibratory and planetary, relative to the fixed stars. The count includes every screw on both sides of the piano lid hinge and every chassis fastener in the car.


 * A conceptual moving part counts as a single part regardless of its actual construction. For piano, key+hammer+string counts as 3, for car drivechain+camshaft+valve counts as 3.


 * A moderate view can be to count Every saleable replaceable part that moves in contact with another saleable replaceable part during normal continual use of the piano or car. For the car, the dealer's parts list is a guide. We may assume that a piston (with rings, gudgeon, connecting rod and big end shells) or a wheel bearing (preassembled with rollers and oil seals) count each as one. A piano key action should be separated into parts than a qualified repairer would consider replacing. This piano repairer estimates 12,000 action components. DroneB (talk) 19:59, 30 September 2018 (UTC)


 * Every component of every link in the timing chain would give you about a thousand moving parts. Your excellent attempt at stratifying the terminology is important, in this trivial problem.Greglocock (talk) 22:53, 30 September 2018 (UTC)
 * That's the 2nd example of intellectual snobbery on this thread. It says more about the writers of such things than anything else.  --   Jack of Oz   [pleasantries]  08:47, 1 October 2018 (UTC)


 * The Question is the famous comparing Apples and oranges nonsense. A Piano is meant to play 88 notes with a volume and dampening like the pianist intends, a engine is meant to provide a predefined jet flexible, efficient and secure transformation of fuel to rotation and Torque. The answer always causes the new question: "Yes/No, so what?" --Kharon (talk) 21:02, 1 October 2018 (UTC)
 * The OP raised the question because his friend made a statement about it. It seems like a reasonable question to ask. A more apples-and-apples question might compare a piano to a harpsichord. But the apples-and-oranges nature of the question is the point. ←Baseball Bugs What's up, Doc? carrots→ 21:20, 1 October 2018 (UTC)
 * Kharon, it depends on one's perspective. Yours is not useful here. Keep it simple.  A piano is an object composed of many parts, some of which move when the object is in operation.  A car is an object composed of many parts, some of which move when the object is in operation. How do the numbers of moving parts compare?  --   Jack of Oz   [pleasantries]  09:28, 2 October 2018 (UTC)
 * We may simplify the comparison to count the numbers of parts that move simultaneously . The wretched inadequacy of my piano playing ability is apparent when I encounter the 7 - gasp 7 -note chord in the 10th bar of Debussy's Clair de Lune. Although the piano is capable of playing all its 88 notes simultaneously under protest (from anyone within earshot), it will never Deo volente be asked to do so. The designer of the Yamaha PortaSound PSS-280 electronic keyboard seems in agreement because this instrument simply refuses to emit more than 7 piano notes at once. Can it be mere serendipity that an East German car was marketed with a 3-cylinder 2-stroke engine that has exactly 7 moving parts? Enough has been said and now like God we should rest on the 7th. DroneB (talk) 14:05, 2 October 2018 (UTC)
 * The seventh? DMacks (talk) 14:30, 2 October 2018 (UTC)
 * I fear the seventh both because 7 8 9, and to face an unlucky number 13 is risky. So I'll quietly take the fifth. DroneB (talk) 16:56, 2 October 2018 (UTC)


 * Ok Jack of Oz . Let me help you on your perspective then. The Volkswagen Group 7993ccm W16 engine is a 16 cylinder 64 valve quad-turbocharged engine, that you can find in the Bugatti Veyrons and Bugatti Chirons and some Bentley models. It should beat any piano regarding number of moving parts since it already has almost as many valves (64) as a piano has keys. Given all the additional moving parts (for example in the fuel injection for 16 cylinders, oilpumps, fuelpumps, waterpumps, power generator, Starter (engine), Distributor, turbochargers etc.) a piano misses, lots of engines probably have more and a few very likely even more that double the moving parts. Btw. a 16 cylinder is not even the top of existing, build combustion engines in cylinder count. And your dear friend compared a piano to a whole car?


 * B.t.w. why are these pianos so damn expensive? Just cut a tree and you have enough material for the frame and mechanics for 5-10 pianos. How does Steinway get away with asking 81 000 $ for a single one? ---Kharon (talk) 14:37, 2 October 2018 (UTC)
 * Yeah, a Steinway is just a tree cut into pieces and re-arranged. --jpgordon&#x1d122;&#x1d106; &#x1D110;&#x1d107; 14:10, 3 October 2018 (UTC)
 * How does Barnes and Noble get away with asking $10 for a book? The price of paper and ink is not even a tenth of that. Tigraan Click here to contact me 16:10, 3 October 2018 (UTC)
 * Somewhat bringing this back to the original topic, have you seen what those damn Germans are up to? Steel etc is a little bit more expensive than wood, still how on earth can they can justify that price tag for a BMW i8. I mean they aren't as bad as the Italians or ole Musky, but still..... Nil Einne (talk) 17:02, 6 October 2018 (UTC)

Berry
What berry is it? Grows this month along a public sidewalk in Warsaw, quite small, about the size of a blackcurrant. I'm planning to pick them for eating, if they're non-toxic, so would like to know the species with absolute certainty. Brandmeistertalk  15:51, 30 September 2018 (UTC)


 * Looks a bit like a cotoneaster - if so the berries are not considered edible. Mikenorton (talk) 20:49, 30 September 2018 (UTC)
 * I agree, looks very like a cotoneaster to me. DuncanHill (talk) 23:57, 30 September 2018 (UTC)
 * I disagree. The leaves in the picture are obtuse - not "ovate to lanceolate in shape". The fruits are borne singly or pairs close to the stem in the pictures - not on a corymb. I will try to track down a better candidate. 196.213.35.147 (talk) 13:37, 1 October 2018 (UTC)
 * Looks like it could be a cotoneaster after all. I'm going with Cotoneaster microphyllus var. glacialis 196.213.35.147 (talk) 14:01, 1 October 2018 (UTC)
 * "These berries are, however, of only doubtful or low toxicity" from Poisonous Plants in Britain and their effects on Animals and Man by the UK Ministry of Agriculture, Fisheries and Food.
 * Also "...as so often, the berries aren’t pleasant to eat. With the Cotoneaster, it is not so much that the taste is unpleasant, though it is, it is that the berries aren’t at all juicy and the texture is powdery. Even birds aren’t that anxious to eat the berries" ';'The Poison Garden Website''. Alansplodge (talk) 14:47, 2 October 2018 (UTC)

Why do tinyish spiders often rappel when chased indoors?
Why don't they just jump off without expelling silk? They probably can't fall as fast as freefall while making silk and such a small creature might not even be injured by terminal velocity. Or did blowing away in the wind on a 1-thread parachute save more spider lives than "freefall and run" in its original outdoor habitat and the instinct remains? Sagittarian Milky Way (talk) 20:01, 30 September 2018 (UTC)


 * Our article ballooning (spider) may help. Mikenorton (talk) 20:57, 30 September 2018 (UTC)


 * You refer to "its original outdoor habitat". I very much doubt whether a spider, whether spiderling or adult, has either any concepts of "outdoors" and "indoors", or the perceptual abilities to tell the differences bearing in mind their size relative to a human-dimensioned structure. {The poster formerly known as 87.81.230.195} 90.217.102.65 (talk) 09:33, 1 October 2018 (UTC)


 * It goes without saying, as it is implied in OP's "and the instinct remains".
 * But even if spiders could distinguish indoors from outdoors (which should be possible, as there are so many differentiating factors they could evaluate: average wind speed, temperature, direction and intensity of infrared radiation and polarized light, smell), why should they just jump off without expelling silk? How could this be a selective advantage? Freefall speed is not the only relevant factor, another would be for example that the thread gives the spider a chance to withdraw from any less than optimal landing place, like water or perhaps the vicinity of predators and carnivorous plants or fire. 194.174.73.80 (talk) 13:31, 1 October 2018 (UTC) Marco Pagliero


 * If you really are asking how it could be a selective advantage, that's obvious: freefall speed could be the most important factor. I've no idea whether it is, but for what it's worth, the ballooning article doesn't seem to give any indication that the spiders can direct their flight. That would seem to imply that the other factors you mention are not significant. HenryFlower 14:49, 1 October 2018 (UTC)
 * Please, you apparently did not read carefully the original question: it asks, why do small spiders "often rappel when chased indoors". Rappel has nothing to do with ballooning but instead describes a spider dropping e.g. from the ceiling on a line of silk. Even if the spider has no control on the direction, the thread allows it to stop and even to reverse the fall if it wishes so. In the context of rappel (not ballooning), my suggestions are of course significant.
 * And secondly you did not read carefully my own question, which read: "How could it be a selective advantage for a spider to just jump off without expelling silk?", this is the opposite of the question you seem to believe you are answering.
 * While for your post to be significant at all you should prove or at least make credible that such small animals as "tinyish spiders" can indeed be damaged when free falling from any height (We are not talking of Migale or Tarantula). 194.174.73.80 (talk) 16:35, 1 October 2018 (UTC) Marco Pagliero Berlin
 * "Migale"? Is there an article? ←Baseball Bugs What's up, Doc? carrots→ 16:40, 1 October 2018 (UTC)
 * Sorry, "Migale" is not English, you are looking for Mygalomorphae 194.174.73.80 (talk) 16:51, 1 October 2018 (UTC) Marco Pagliero Berlin
 * Marco, you've misunderstood completely. Not producing silk maximises freefall speed and so allows the fastest escape from the chaser. There's a fairly obvious selective advantage to that. (The ballooning issue is not so relevant, but you got that wrong too: SMW asked about "blowing away in the wind on a 1-thread parachute".) HenryFlower 20:41, 1 October 2018 (UTC)
 * No, the question was "Why do tinyish spiders often rappel when chased indoors", while the parachute sentence you are citing was enbedded in a tentative response to this question but it doesn't imply the tinyish spiders SMW is chasing do actually try to balloon away (see the next sentence: 'can't fall as fast as freefall while making silk'). So I ask again, why should it be an advantage to spring without a thread beeing indoors if it is an advantage to spring with a thread beeing outdoors?
 * Your 'fairly obvious selective advantage' is not meaningful: whether you see the landing speed or the freefall speed as important, chased spiders never try to escape by ballooning but either by running or by rappeling, so your argument is pointless: ballooning is not a strategy for escaping when beeing chased and is not initiated by jumping without a fixed thread.
 * Well, even I can be wrong, so I'd like SMW to confirm whether he has ever seen a chased spider actually try to escape by 'blowing away in the wind on a 1-thread parachute' (Even our article on ballooning doesn't suggest anything like this) 194.174.73.80 (talk) 16:16, 4 October 2018 (UTC) Marco Pagliero Berlin
 * That was my mistake, I didn't know that thing baby spiders do to disperse was multiple threads. I have never actually seen a spider balloon but one of those nasty ballooners blew in my face once. That was my guess of why they have the rappelling instinct even though there's no wind - that they'd either cut the thread if wind gave them enough sideways momentum and squirt more thread to be blown away on or they'd glue it to the wall weakly enough that it breaks off if the spider brakes suddenly in the first quarter cycle of swinging in the wind like a pendulum. And then blow away on that thread. Sagittarian Milky Way (talk) 19:53, 4 October 2018 (UTC)
 * It doesn't have to be a selective advantage in all circumstances. It only has to be a selective advantage in a sufficient number of instances to provide a meaningful impetus to survival and reproduction. Bus stop (talk) 16:57, 1 October 2018 (UTC)

File:Amrum.grass.jpg
Location known, but wanted to check something. The grass here gives way to a different cover, over what I am thinking is the landward portion of dunes?

Which articles should I look at to epxand the description? — Preceding unsigned comment added by ShakespeareFan00 (talk • contribs) 22:52, 30 September 2018 (UTC)


 * The green and purple stuff? Heather - so see Ericaceae, Erica, and Calluna vulgaris. DuncanHill (talk) 23:54, 30 September 2018 (UTC)


 * This paper should help narrow the options down. Mikenorton (talk) 16:57, 1 October 2018 (UTC)
 * This one may be more helpful (by the same botanist). Mikenorton (talk) 17:05, 1 October 2018 (UTC)


 * Thanks caption updated accordingly, if someone wants to review. ShakespeareFan00 (talk) 09:04, 2 October 2018 (UTC)