Wikipedia:Reference desk/Archives/Science/2016 October 20

= October 20 =

Surviving a 130-degree hyperthermia
I believe it's possible that people can survive a 130-degree F hyperthermia. I speculate there was a person whose body temperature reached 133 deg. F and survive, which is a world record for the highest body temperature to reach and survive. What do you think of this oddity? Planet Star  04:51, 20 October 2016 (UTC)
 * Where did you see the 133 degrees report? ←Baseball Bugs What's up, Doc? carrots→ 05:52, 20 October 2016 (UTC)
 * That was merely my guess and I did not see the report of that. Planet  Star  22:28, 20 October 2016 (UTC)
 * Apparently, the highest recorded non-fatal body temperature was is 115.7°F (46.5°C) achieved by one Willie Jones of Atlanta in 1980. Our article Orders of magnitude (temperature) cites this website, which cites the Guinness Book of Records.  This is a rather more reliable citation for a body temperature of 113°F (45°C).  But nobody has survived anything close to 130°F. Tevildo (talk) 05:54, 20 October 2016 (UTC)
 * The OP may be misremembering reports of survivable sustained external temperatures, which of course can be much higher than internal temperatures, particularly in an experimental laboratory setting. {The poster formerly known as 87.81.230.195} 90.197.27.88 (talk) 15:09, 20 October 2016 (UTC)
 * One demonstration (I can't find the ref at the moment) had a man and a steak in a high temperature chamber. The steak ended up cooked while the man was unharmed. IIRC they kept the humidity near 0%, had a large fan blowing air over man and steak, and allowed the man to drink a lot of water and take pills to replenish water and electrolytes lost through sweating. So it was basically a demonstration of how well sweating cools you. --Guy Macon (talk) 04:38, 21 October 2016 (UTC)
 * Staying with a Finnish family many years ago, they cooked their sausages by hanging them in the sauna while we were using it. Our article suggests that the air temperatures in a Finnish sauna are "typically between 70 and 100 °C" (158 and 212 °F). It was certainly bloody hot. Alansplodge (talk) 11:08, 22 October 2016 (UTC)
 * Were they higher then you where hot air rises? Sagittarian Milky Way (talk) 16:21, 23 October 2016 (UTC)
 * About head height when we were sitting down, if I recall correctly. The difference was that we got up and jumped in the lake every fifteen minutes or so and then drank some beer before going back again, while the sausages stayed there all afternoon. Alansplodge (talk) 20:55, 23 October 2016 (UTC)
 * Charles Blagden first performed this experiment in 1775 (ref), although it's doubtless been performed under more controlled conditions since then. Tevildo (talk) 12:42, 22 October 2016 (UTC)

Walk thousands of miles without losing weight
I think it's possible to walk from New York to Los Angeles without losing a single pound. Do you agree? Planet Star  04:51, 20 October 2016 (UTC)
 * In how much time? ←Baseball Bugs What's up, Doc? carrots→ 05:52, 20 October 2016 (UTC)
 * Besides what BB has said, it depends on what your body was like before you started, what & how much you eat and drink and how all these (including exercise) were before you started this journey, etc. But the answer is surely yes if you don't have any restrictions. Plenty of people put on weight despite regular exercise. (Actually it can be quite easy to put on weight if you hardly exercise at all and weren't very overweight due to increasing muscle although walking from New York to LA would generally be a resonable amount of exercise.) The driving distance between New York and LA is only ~4500 km which means if you take 13 years it's only about 0.95 km a day which is by no means a lot. Nil Einne (talk) 06:36, 20 October 2016 (UTC)
 * if you connect your body to a source of automated nutrition suppply set at isotone (crysis nanosuit, halo spartan model), then yes.Minimobiler (talk) 12:22, 20 October 2016 (UTC)
 * The ancient Roman weight unit libra or pound, equal to about 328.9 g, was adopted as a coinage unit "Tower pound" (of silver) in the reign of King Offa of Mercia and is source of the £ abbreviation of £sd i.e. £ibrae, solidi, and denarii. Traveler's cheques for values in pounds were first issued in 1772, can still be bought and are touted as "Completely safe: if they get lost or stolen they'll be replaced.". Their issuers of these un-losable pounds never mention the pounds they gain in interest from lending the pounds you paid them to other borrowers, which is part of the reason for declining use of the cheques. AllBestFaith (talk) 16:38, 20 October 2016 (UTC)


 * Obese people will need to lose weight before they can reach the physical fitness required for this. Count Iblis (talk) 20:20, 20 October 2016 (UTC)
 * Again, without any restrictions this is surely wrong. If we're talking about classicial definitions like those using BMI, obesity covers a very wide range of physical conditions. 0.95 km is hardly a lot of exercise. (It's probably enough that many, but not all, obese people will lose weight again dependent also on all the conditions before and during.) If we expand it even further, we can get it down to 0.4 km which if you start at age 20, will mean you're still far from elderly before you finish. And 0.4 km is hardly that much exercise at all. Of course you need some way to get the food and someone to rest in between, which is perhaps what Minimobiler was getting at but again without restrictions you could sleep in a campervan or something and the food and water could be brought to you, likewise the campervan cleaned etc. Even if you're using stricter definitions of obesity, AFAIK most of them would still allow someone who can walk 0.4 km or 0.95 km a day to be obese. Of course at the outer range, you have people who can't even get out of bed, but you said obese people, not severely obese people. Nil Einne (talk) 02:20, 21 October 2016 (UTC)
 * Dunno about your definition of Obese, but with a BMI of 36 I used to go walking for 7 days carrying my own tent and food (22kg pack), and rarely lost weight. I did lose weight when I walked to Everest base camp, probably slight dehydration, it was only a couple of kg. Greglocock (talk) 06:36, 22 October 2016 (UTC)

copper pot vs copper pot filled with water
which helps cool or melt things faster? — Preceding unsigned comment added by Minimobiler (talk • contribs) 12:19, 20 October 2016 (UTC)
 * Water has a higher specific heat than copper. That should help you figure out how each responds to changes in temperature.  -- Jayron 32 12:24, 20 October 2016 (UTC)

but the conduction rate. it is lower, much. — Preceding unsigned comment added by Minimobiler (talk • contribs) 12:37, 20 October 2016 (UTC)
 * Conduction rate is controlled by Newton's law of cooling. -- Jayron 32 12:38, 20 October 2016 (UTC)
 * We can also write Fourier's law, (which simplifies down to Newton's law in many cases), but also accounts for a material-specific conduction constant.
 * I think we need the original question to be phrased more precisely and specifically before we start lobbing equations at it. Are you envisioning a copper pot on a stove, with new heat being added?  How much water?  What are you heating?  At what temperatures?  ...and so on.  These details will impact the way we model the heat transfer, which might change the answer you're looking for.
 * For example, last week I took a safety training class at my local fire station, and I learned all about flashover. In a small kitchen fire, heat is conveyed convectively and conductively as hot material physically touches other flammable fuels, and as hot flame and smoke billow around the environs.  But in a really big fire (like when the whole room starts burning), the temperatures rise really rapidly.  Thanks to the Stefan–Boltzmann law, we know that infrared emission, like all other electromagnetic radiation, rises with the fourth power of temperature - so once your room is up to, say, a thousand degrees, a great quantity of heat starts travelling at the speed of light.  This is faster than conductive heat transfer; it is faster than convective heat transfer; it is faster than supersonic detonation.  ...And this "exotic" mode of heat flow occurs during ordinary structure-fires.  When flashover occurs, it becomes the primary mode of ignition - even if only a small percentage of total heat transfer (in joules) occurs by this mode, it occurs so rapidly (think about watts, or joules-per-second, at the characteristic time-scales of a beam of infrared traveling across your room).
 * So if you're cooking your copper pot inside a house fire, we can't use simplified math: we have to go back to first principles of physics. How does heat flow?  (Heat conduction, convection, and radiation).  How do we quantify the rate of heat flow for each mode?  (Our articles point you toward the right equations).  In which circumstances can we totally ignore some of the details, and use a simpler equation?  (This would be a great homework question!)
 * Nimur (talk) 14:52, 20 October 2016 (UTC)

If you put wings on to a Tesla, would it fly?
If you put the drive train from a Tesla and put it into an airplane, would it fly?

The Tesla Model S P100D does 0-60 mph in only 2.5 seconds. It has 760bhp, but it weighs 2,100kg - of that, about 500kg is battery. It has a range of maybe 300 miles and costs US$135,000. By comparison, a Cessna 172 has four seats and weighs 800 kg to 1,100 kg, depending on fuel/cargo. It will cruise at 140 mph, but it only needs 160 bhp.

Pigs can't fly, but what if you put wings on a Tesla?--2A02:C7D:42AB:3800:253B:991C:30A:30E6 (talk) 17:18, 20 October 2016 (UTC)


 * Can assure you that pigs don't have any trouble flying as long as they can gain enough kinetic energy to get off the ground. Here, in the UK we have often flown cars too. --Aspro (talk) 22:06, 21 October 2016 (UTC)


 * Actually, some pigs can in fact fly. 2601:646:8E01:7E0B:40E5:EEF0:65B8:D229 (talk) 23:17, 23 October 2016 (UTC)


 * Wikipedia has an article titled Flying car (aircraft) which covers both speculative and actually build flying cars. -- Jayron 32 17:23, 20 October 2016 (UTC)
 * See also Electric aircraft for some real-world examples. Tevildo (talk) 17:59, 20 October 2016 (UTC)


 * Homebuilt aircraft can have many different types of motors, including chainsaw and motorcycle motor, so I would not be surprising to see a flying plane with a Tesla motor. However, as the LA Times reports, electric airplanes still have some challenges before it. --Llaanngg (talk) 12:56, 21 October 2016 (UTC)


 * A fuel cell could probably be more effective as a power source than a battery in terms of having a better weight/energy ratio. Roger (Dodger67) (talk) 13:18, 21 October 2016 (UTC)


 * Note that you would need to add a lot of weight to the Tesla in the wings, if they are to be big enough and strong enough to support the weight of the car, and include all the controls and control surfaces needed to steer a plane. StuRat (talk) 17:22, 23 October 2016 (UTC)