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How does a large helium balloon (e.g. a blimp or something the size of a hot-air balloon) descend? Hydrogen isn't particularly rare, so you could probably just let off some of it without losing a lot of money, and with a hot-air balloon, you can presumably just stop heating the air, but re-filling the Goodyear Blimp with helium sounds absurdly expensive. <helium balloon descend> on Google is all about party balloons and the like. Nyttend ( talk) 03:02, 31 October 2016 (UTC)
In her book,
The Good Women of China by journalist
Xue Xinran, Chapter 5: "The Mothers who Endured an Earthquake" - referring to survivors of the massively destructive
Tangshan earthquake (28 July 1972 1976). It includes a mother's 1992 account (17 years after the event) of her 14-year-old daughter, "the lower half of [whose] body was wedged between the reinforced concrete slabs of the wall...", and later findings that "her legs had been crushed to a pulp...[and] her pelvis had broken under the pressure." For two weeks, "food and medicine were brought to her every day and someone came to nurse her..." and she was "exposed to the elements" while futile efforts to free her continued. The girl attests to "numbness" without pain in her lower body and is able to speak and even sing to the gathered crowd before she expires "after fourteen days and two hours."
My question: is it plausible to survive two weeks trapped with a crush injury?* In the widely publicized case of 13-year-old Omayra Sánchez in Armero, Colombia, trapped by mudslide debris in the aftermath of a 1985 volcanic eruption, she survived a documented 60 hours. Despite there being no way to compare the nature and extent of the two girls' injuries, my query is about triage and treating survivors of crush injuries, while they're trapped and after their extrication, given the possible complications of crush syndrome along with other factors facing rescue teams. *(My intent is to expand the page content.) -- Deborahjay ( talk) 10:23, 31 October 2016 (UTC)
OP clarifies: Particularly, how long can a person survive with lower extremities pinned by debris, i.e. vital organs unimpaired but field amputation impossible. -- Deborahjay ( talk) 11:13, 31 October 2016 (UTC)
: Deborahjay, it was in 1976, not 1972. -- Jack of Oz [pleasantries] 18:15, 31 October 2016 (UTC)
I am interested in the error margin contained in the WGS84 estimation of a longitudinal quadrant at 10,001,965.729 meters, corresponding to a meridian of 40,007,862.916 meters. I ask this for three main reasons:
Can anyone provide me with current or updated values for the measurement uncertainty inherent such length estimations ? — 79.113.212.81 ( talk) 12:11, 31 October 2016 (UTC)
Clarification: I am curious about how the meter would have to be redefined in terms of the speed of light so as to make the length of a (mean ?) terrestrial meridian match the original historical definition of 40,000 km as close as humanly possible. This has been the meaning and intent of my question. I've calculated c = 299,733,5381⁄2 m*/s , where m* represents the `new` or `meridional` meter. However, such precision would be absurd in light of the above. I am curious about the range which the value of c can span (not in the sense that c actually varies, but in the sense that the same constant can be numerically expressed in various ways, depending on the actual range within which our knowledge of the terrestrial meridian can vary). — 82.137.53.158 ( talk) 20:15, 31 October 2016 (UTC)
Further Clarification: I honestly couldn't care less about either WGS84 or global positioning systems. (The only reason I even mentioned its name was because I gave a number, and it seemed common sense to mention the source of one's information, that's all. Apparently, this was a complete mistake, since it completely detoured the focus of the conversation). The only thing I care about is determining the smallest possible interval on which the length of terrestrial meridian(s) is known to exist with absolute certainty; e.g., something like 40,007.5-40,009.5 km, but I'm not sure if this is either the smallest, OR if it's limits are even 100% certain. — 79.115.135.102 ( talk) 11:20, 1 November 2016 (UTC)
In 1791 a quarter of the meridian i.e. the distance from the Equator to the North Pole via Paris, was declared 10 000 000 meters exactly by definition. Since then the actual physical distance is not known to have changed and it has been studied since 1795 by the French Bureau des Longitudes. They do not claim that measurements on the ground with millimeter repeatability are possible. What has happened is that the meter standard was changed by declaration in 1983 to the distance travelled by light in vacuum in 1/299792458 of a second, equivalent to saying light travels at 299792458 meters per second exactly by definition. It is the deliberate exactness of these integers that allow an appearance of unrealistic precision when one makes an estimate in "new" meters of the meridian by Least squares regression of the best available data. AllBestFaith ( talk) 00:53, 1 November 2016 (UTC)
Does anyone more familiar than I with cue sports such as billiards, snooker or pool happen to know what the relevant standards are for the sphericity and surface smoothness of a ball? If there's a difference between "match grade" and "typical", then either would really do. I can find standards for diameter, and variations in permitted diameter, but that's not the same thing.
(Then does anyone know how this compares to the Earth? - I'm assuming
Everest at 8,848m,
Marianas Trench at 11,000m and a prolateoblate spheroid of about 1/300 flattening)
Andy Dingley (
talk) 18:36, 31 October 2016 (UTC)
There is some commentary here [2] about the roughness suggesting the earth is definitely rougher than a billiard ball. It isn't an RS but based on someone's personal estimation from balls they have studied although also looks at photos of balls ( [3]) and other things. But given that the WPA didn't respond it may be the best you'll find. (Although it's possible the person just got unlucky. And I suspect someone like NdGT is more likely to get a response.) There is also some commentary on the images and other things here [4] which comes to the same conclusion. Also mentioned in the first link is [5] as there are some comments there which may be helpful. (Although there are so many comments there including of other stuff it's hard to find the good ones, but I did see some discussion of smoothness etc. Maybe Paul Hutch's comments are the key ones.)
IMO I would be willing to conclude from these that the earth is not as smooth as a normal/typical undamaged billiard ball. (Similar conclusions are reached about the roundness although I'm a bit confused by this since as mentioned by others, some sources conclude the earth isn't even within the spec for roundness.)
Whether the earth is as smooth (or round) as a billiard ball technically can be I'm not sure. Not legal advice but if the WPA doesn't actually specify smoothness, it may be such a ball is indeed technically allowed. Unless there's some loose policy like the referee being able to decide if a ball is acceptable condition without any definite specification of what this entails. (It'll probably help if both players agree they want a different ball/s which I suspect will normally be the case.) In any event, if people regularly start producing such balls, it may be they'll fix their specification.
Nil Einne ( talk) 23:46, 31 October 2016 (UTC)
The billiard sharp who any one catches, His doom's extremely hard — He's made to dwell — In a dungeon cell On a spot that's always barred. And there he plays extravagant matches In fitless finger-stalls On a cloth untrue With a twisted cue And elliptical billiard balls
I don't mean in the sense of a mad spiritual cure for homosexuality, but more in the sense of an exposure to different stimuli. For example, if a man has access to one type of porn or the other, would he develope different tastes? Is there anything like acquired tastes in the sexual field? -- Llaanngg ( talk) 23:42, 31 October 2016 (UTC)
Science desk | ||
---|---|---|
< October 30 | << Sep | October | Nov >> | November 1 > |
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. |
How does a large helium balloon (e.g. a blimp or something the size of a hot-air balloon) descend? Hydrogen isn't particularly rare, so you could probably just let off some of it without losing a lot of money, and with a hot-air balloon, you can presumably just stop heating the air, but re-filling the Goodyear Blimp with helium sounds absurdly expensive. <helium balloon descend> on Google is all about party balloons and the like. Nyttend ( talk) 03:02, 31 October 2016 (UTC)
In her book,
The Good Women of China by journalist
Xue Xinran, Chapter 5: "The Mothers who Endured an Earthquake" - referring to survivors of the massively destructive
Tangshan earthquake (28 July 1972 1976). It includes a mother's 1992 account (17 years after the event) of her 14-year-old daughter, "the lower half of [whose] body was wedged between the reinforced concrete slabs of the wall...", and later findings that "her legs had been crushed to a pulp...[and] her pelvis had broken under the pressure." For two weeks, "food and medicine were brought to her every day and someone came to nurse her..." and she was "exposed to the elements" while futile efforts to free her continued. The girl attests to "numbness" without pain in her lower body and is able to speak and even sing to the gathered crowd before she expires "after fourteen days and two hours."
My question: is it plausible to survive two weeks trapped with a crush injury?* In the widely publicized case of 13-year-old Omayra Sánchez in Armero, Colombia, trapped by mudslide debris in the aftermath of a 1985 volcanic eruption, she survived a documented 60 hours. Despite there being no way to compare the nature and extent of the two girls' injuries, my query is about triage and treating survivors of crush injuries, while they're trapped and after their extrication, given the possible complications of crush syndrome along with other factors facing rescue teams. *(My intent is to expand the page content.) -- Deborahjay ( talk) 10:23, 31 October 2016 (UTC)
OP clarifies: Particularly, how long can a person survive with lower extremities pinned by debris, i.e. vital organs unimpaired but field amputation impossible. -- Deborahjay ( talk) 11:13, 31 October 2016 (UTC)
: Deborahjay, it was in 1976, not 1972. -- Jack of Oz [pleasantries] 18:15, 31 October 2016 (UTC)
I am interested in the error margin contained in the WGS84 estimation of a longitudinal quadrant at 10,001,965.729 meters, corresponding to a meridian of 40,007,862.916 meters. I ask this for three main reasons:
Can anyone provide me with current or updated values for the measurement uncertainty inherent such length estimations ? — 79.113.212.81 ( talk) 12:11, 31 October 2016 (UTC)
Clarification: I am curious about how the meter would have to be redefined in terms of the speed of light so as to make the length of a (mean ?) terrestrial meridian match the original historical definition of 40,000 km as close as humanly possible. This has been the meaning and intent of my question. I've calculated c = 299,733,5381⁄2 m*/s , where m* represents the `new` or `meridional` meter. However, such precision would be absurd in light of the above. I am curious about the range which the value of c can span (not in the sense that c actually varies, but in the sense that the same constant can be numerically expressed in various ways, depending on the actual range within which our knowledge of the terrestrial meridian can vary). — 82.137.53.158 ( talk) 20:15, 31 October 2016 (UTC)
Further Clarification: I honestly couldn't care less about either WGS84 or global positioning systems. (The only reason I even mentioned its name was because I gave a number, and it seemed common sense to mention the source of one's information, that's all. Apparently, this was a complete mistake, since it completely detoured the focus of the conversation). The only thing I care about is determining the smallest possible interval on which the length of terrestrial meridian(s) is known to exist with absolute certainty; e.g., something like 40,007.5-40,009.5 km, but I'm not sure if this is either the smallest, OR if it's limits are even 100% certain. — 79.115.135.102 ( talk) 11:20, 1 November 2016 (UTC)
In 1791 a quarter of the meridian i.e. the distance from the Equator to the North Pole via Paris, was declared 10 000 000 meters exactly by definition. Since then the actual physical distance is not known to have changed and it has been studied since 1795 by the French Bureau des Longitudes. They do not claim that measurements on the ground with millimeter repeatability are possible. What has happened is that the meter standard was changed by declaration in 1983 to the distance travelled by light in vacuum in 1/299792458 of a second, equivalent to saying light travels at 299792458 meters per second exactly by definition. It is the deliberate exactness of these integers that allow an appearance of unrealistic precision when one makes an estimate in "new" meters of the meridian by Least squares regression of the best available data. AllBestFaith ( talk) 00:53, 1 November 2016 (UTC)
Does anyone more familiar than I with cue sports such as billiards, snooker or pool happen to know what the relevant standards are for the sphericity and surface smoothness of a ball? If there's a difference between "match grade" and "typical", then either would really do. I can find standards for diameter, and variations in permitted diameter, but that's not the same thing.
(Then does anyone know how this compares to the Earth? - I'm assuming
Everest at 8,848m,
Marianas Trench at 11,000m and a prolateoblate spheroid of about 1/300 flattening)
Andy Dingley (
talk) 18:36, 31 October 2016 (UTC)
There is some commentary here [2] about the roughness suggesting the earth is definitely rougher than a billiard ball. It isn't an RS but based on someone's personal estimation from balls they have studied although also looks at photos of balls ( [3]) and other things. But given that the WPA didn't respond it may be the best you'll find. (Although it's possible the person just got unlucky. And I suspect someone like NdGT is more likely to get a response.) There is also some commentary on the images and other things here [4] which comes to the same conclusion. Also mentioned in the first link is [5] as there are some comments there which may be helpful. (Although there are so many comments there including of other stuff it's hard to find the good ones, but I did see some discussion of smoothness etc. Maybe Paul Hutch's comments are the key ones.)
IMO I would be willing to conclude from these that the earth is not as smooth as a normal/typical undamaged billiard ball. (Similar conclusions are reached about the roundness although I'm a bit confused by this since as mentioned by others, some sources conclude the earth isn't even within the spec for roundness.)
Whether the earth is as smooth (or round) as a billiard ball technically can be I'm not sure. Not legal advice but if the WPA doesn't actually specify smoothness, it may be such a ball is indeed technically allowed. Unless there's some loose policy like the referee being able to decide if a ball is acceptable condition without any definite specification of what this entails. (It'll probably help if both players agree they want a different ball/s which I suspect will normally be the case.) In any event, if people regularly start producing such balls, it may be they'll fix their specification.
Nil Einne ( talk) 23:46, 31 October 2016 (UTC)
The billiard sharp who any one catches, His doom's extremely hard — He's made to dwell — In a dungeon cell On a spot that's always barred. And there he plays extravagant matches In fitless finger-stalls On a cloth untrue With a twisted cue And elliptical billiard balls
I don't mean in the sense of a mad spiritual cure for homosexuality, but more in the sense of an exposure to different stimuli. For example, if a man has access to one type of porn or the other, would he develope different tastes? Is there anything like acquired tastes in the sexual field? -- Llaanngg ( talk) 23:42, 31 October 2016 (UTC)