Wikipedia:Reference desk/Archives/Science/2015 September 4

= September 4 =

Which is the best drink to replace fluids you have lost by sweating and why?
Which is the best drink to replace fluids you have lost by sweating and why? — Preceding unsigned comment added by 5.30.89.238 (talk) 05:53, 4 September 2015 (UTC)
 * I don't know if this will help but here is "Sports Drinks vs. Water ". Bus stop (talk) 06:09, 4 September 2015 (UTC)


 * There have been numerous experiments in which participants were made to exercise and sweat, and then rehydrate with various liquids. Various outcomes were measured. It's generally found that in this situation, water and sports drinks (things like gatorade) perform either equally or the gatorade performs slightly better. It should be noted that the consequence of sweating during exercise (assuming you're talking about exercise, or simply being outside on a hot day) is only mild dehydration. In cases of extreme dehydration, such as while suffering from dysentery, the gatorade or similar beverages perform vastly better than water by various measures. . Someguy1221 (talk) 06:10, 4 September 2015 (UTC)


 * Depends how much you sweat, and how fast you want it back. If you're literally losing buckets, like a combat athlete cutting weight, you'll want saline through an IV drip. Drinking the same amount of any fluid orally can lead to water intoxication and/or just doesn't fit/makes you hurl. For medium rehydration, use whatever's tastiest and non-diuretic; you'll drink more if you like the flavour. For light and often rehydration (like, non-athlete on a warmish day), plain water is best, just for being plain. Same perks, less sugar and salt. If you want to rehydrate while dehydrating, salty sweet Gatorade is still the king. InedibleHulk (talk) 06:21, 4 September 2015 (UTC)


 * If you're pedantic and drinks need to be taken orally (or stupid and needles are always bad), Pedialyte's the drink for heavy sweaters. InedibleHulk (talk) 06:43, 4 September 2015 (UTC)


 * I tend to agree. Now here is a simplistic answer to the 'why' . Any plain water will hydrate one but to do it rapidly one needs it to enter the cells through the  Aquaporins. However, that could quickly dilute the potassium/sodium osmotic balance in the cells.  A bad thing ( look at a few blood cells in distilled water under a microscope and they swell up and burst). To prevent this, more sodium and potassium has to be pumped into the cells (against the osmotic pressure gradient) (said this was a simplistic explanation didn't I). This pumping requires energy. That energy is provided by glucose. So a fast re-hydration fluid need these three components to be present.  Now coming to the question of what most efficacious. Any re-hydration fluid that supplies the cells needs, will work as well as any other.  My Oxford Textbook Of Medicine (by the Oxford University Press) page 12.135 suggests, that for each liter, one adds Sodium Chloride (table salt) 3.5 grams, Sodium Bicarbonate 2.5 grams, Potassium Chloride 1.5 grams, Sucrose (table sugar) 40 grams.  This may not impress people with more money than sense - as it is dirt cheap to make and does not come in fancy bottles.--Aspro (talk)


 * We have a brief article; Sports drink. Alansplodge (talk) 12:38, 4 September 2015 (UTC)


 * Ignore sports drinks. Water is fine, but milk may be better. Bazza (talk) 14:28, 4 September 2015 (UTC)


 * Unless you're one of the countless millions of people who have a lactose intolerance or a milk allergy. -- Jayron 32 15:11, 4 September 2015 (UTC)


 * Which is why I qualified my comment with "may" for the countless millions who don't but think that expensive sports drinks are the best. Bazza (talk) 16:15, 4 September 2015 (UTC)


 * Even for those lucky few, mixing milk and sweat can seriously haunt a gym bag. They never smell good, but sour dairy's a whole other level (though still below eggs). Water doubles as a splashable coolant, and while you don't want to be sugarcoated, a bit of wayward energy/sport drink during a high-paced timeout is just sticky, not stinky. InedibleHulk (talk) 07:50, 5 September 2015 (UTC)


 * The issue of milk aside, I think the article Bazza linked to (although I admit I am fairly wary of it particularly with the milk recommendation), as well as our own article linked above highlights an important point which has been mostly missed in this discussion. Both of these seem to concur with what I've read before. The actual evidence for the benefit of sports drinks be they home made or commercially made and whatever the precise concentrations compared to water is fairly limited in non extreme situations. If you've going to be vigorously exercising for 2 hours or something then perhaps the sports drink is worth considering. If you're just in for a 30 minute session or an hour session of moderate exercise, perhaps not. Note also that the OP didn't mention exercise at all. There will obviously be some variation depending on temperature level of fitness, type of activity (I mean besides how vigirous the exercsie is) and probably at what stage of exercise. E.g. I don't know the quality of science behind it, but this site for runners recommends water, a heavily diluted sports drink (I suspect this is more than 50/50) or water with added electrolytes (I think excluding any significant carbohydrates) for hydration during a run, but does recommend a drink with carbohydrate or protein after a run. BTW I would be wary of any source which comes up with a universal figure of optimal concentrations for all situations, it sounds like something unlikely to be really backed by any science. Nil Einne (talk) 05:38, 5 September 2015 (UTC)


 * Gatorade is pretty consistently backed by the American College of Sports Medicine, which is pretty consistently backed by Gatorade. It's a system high in asclepiacaduceal ouroborolytes, but a conflict of interest doesn't always entail a snake in the grass. InedibleHulk (talk) 07:50, 5 September 2015 (UTC)


 * Backed for what purpose? I.E. for what activities (time, strength and type), under what conditions, and at what stage? And mostly importantly, backed based on what research? Nil Einne (talk) 16:21, 5 September 2015 (UTC)
 * For exercise events of duration greater than 1 hour. All of them, I guess. They don't mention Gatorade by name, but they describe it. InedibleHulk (talk) 06:26, 6 September 2015 (UTC)
 * I only read the abstract, but despite the sometimes confusing wording it sounds to me like they are only referring to "intense exercise lasting longer than 1 h" not all exercise. Any way, even if it is all exercise of duration greater than 1 hour, this is still more specifically than you initially suggested. In fact the abstract itself says that there's no real evidence that a carbohydrate-electrolyte drink is better than plain water. Nil Einne (talk) 18:20, 6 September 2015 (UTC) Edit: Forgot to mention, but that source does at least include a range rather than a fixed ideal value for the drinks. Nil Einne (talk) 20:06, 7 September 2015 (UTC)


 * A note on sports drinks: The makers must balance it being what you need with what you want, if they expect to sell much. That can lead them to add more sugar than is ideal for health.  (After all, if it contained all the ingredients of sweat, in the same proportions, then it would taste like sweat, and nobody wants to drink that.) StuRat (talk) 16:40, 4 September 2015 (UTC)


 * Good point StuRat. Gatorade contains 21 grams of carbohydrates  per 12 oz serving. . One only needs 20 grams of glucose per litre in order to rehydrate properly. Carbohydrates are good for short term fuel but the body need 'water' to metabolise them – so one needs to drink even more (good  marketing reason to add loads of sugar huh?). And when the body gets too much carbohydrates it turns it into fat, which means one has to exercise more to burn it off. Which requires even more sports drinks to rehydrates again. etc., et cetera. You can fool all the people some of the time and some of the people all of the time, but you cannot fool all the people all the time. So does the OP now know “Which is the best drink to replace fluids you have lost by sweating and why?”--Aspro (talk) 20:36, 4 September 2015 (UTC)


 * Yup. Lots of people I know mix Gatorade (or similar) 50/50 with water for this reason. When drunk straight it's way too sugary. Short Brigade Harvester Boris (talk) 03:40, 5 September 2015 (UTC)


 * To do the math, using Aspro's numbers, 12 ounces is 0.354882 liter, so 21 g of carbs per 12 ounces = 21/0.354882 or over 59 g of carbs per liter. That's almost triple the 20 g amount needed.  Of course, not all carbs are glucose, so there could be some error introduced by assuming they are identical in Gatorade. StuRat (talk) 05:16, 6 September 2015 (UTC)


 * It is also important to have a good meal after exercise that contains some protein (either veg like peas and beans or animal). One needs it, to build up skeletal and muscle mass. High   glycemic drinks  suppress  this natural  appetite. So you're not doing your body any favours by consuming them. Go back to basics and rehydrate first. Then satisfy one's  nutritional needs with real food and not empty calories from  a fancy and  expensive  plastic bottle.--Aspro (talk) 14:51, 5 September 2015 (UTC)
 * One other thing to keep in mind, if you're doing heavy endurance exercise on a warm day, is that in addition to not wanting to get dehydrated or get your electrolytes out of balance, you also don't want to bonk. I don't know whether the sugar in sports drinks is a good aid for not bonking, but it seems at least plausible. --Trovatore (talk) 19:29, 6 September 2015 (UTC)


 * Your statement in British English has a different (2) and amusing meaning! Bazza (talk) 20:19, 6 September 2015 (UTC)


 * Now you know how Yanks feel when a Brit says they plan to go "knock somebody up" (meaning to knock on their door, of course). StuRat (talk) 16:42, 8 September 2015 (UTC)

Magnetized magnet
Let's say I have A magnetized iron bar.How do I weaken its magnetism?2404:E800:E606:25C:A488:362D:8638:B6F1 (talk) 08:36, 4 September 2015 (UTC)


 * Drop it onto concrete (or another hard surface) a few times. For a more reliable method, read Degaussing.    D b f i r s   08:41, 4 September 2015 (UTC)


 * Or heat it up past its Curie temperature--Phil Holmes (talk) 11:51, 4 September 2015 (UTC)

Why have head-phones such thin cables?
My recently deceased head-phones didn't last more than some months. As it happens, they had hair thin cables. Couldn't the manufacturers have built a model with more resilient cables? Does it make any difference to the sound what cable you use to connect loudspeakers to plugs? Or is this just an evident case of planned obsolescence?--Scicurious (talk) 13:34, 4 September 2015 (UTC)
 * They could have. Like anything else, there is a Cost–benefit analysis to be done, in this case the added cost, and thus added price to the consumer.  Less people will buy more expensive goods, so they need to balance the lower sales expected from higher cost goods.  If they make more money as a bottom line by making cheap, disposable stuff that breaks (and needs to be replaced!) every three months, they'll do so.  The first rule of business is maximize profits.  There is no second rule.  -- Jayron 32 13:55, 4 September 2015 (UTC)
 * Yes, but there is also a market for cheap headphones that have cables as light and unobtrusive as possible, so they don't get in the way as you move around. Typically high-quality headphones have pretty robust cables. Looie496 (talk) 14:07, 4 September 2015 (UTC)
 * Exactly what I said. No need for the "but".  -- Jayron 32 14:10, 4 September 2015 (UTC)
 * Excuse me, but it isn't exactly what you said. You didn't say anything about thin cables being better for some purposes.  Perhaps you intended to, but you didn't. Looie496 (talk) 14:31, 4 September 2015 (UTC)
 * Companies produce products to make themselves the most amount of money possible. Are you saying that "making thin cables being better for some purposes" is done by companies with the intent of making less money?  -- Jayron 32 15:23, 4 September 2015 (UTC)
 * The more robust they are, the heavier they are. Most of us don't like heavy stuff hanging off our heads. ←Baseball Bugs What's up, Doc? carrots→ 14:22, 4 September 2015 (UTC)
 * My (fantastic) Sennheiser headphones have a very thick cable. It's also removable; the headphones themselves have a jack, so you can use any cable you want. Now, I think I paid around US$200 for them, but I set out with the intention of buying quality headphones, and did my research before buying. As far as whether the cable you use can affect the sound, it can, to a point. The resistance and impedance of the wire affect the properties of the circuit, so wire that is of poor quality or too thin for the load applied can have an adverse impact. Headphones, and speakers in general, are, after all, electronic devices. Note the phrase "for the load applied"; higher-end headphones are often designed to be used with amplifiers. If you want to learn more start reading up about audio engineering. --71.119.131.184 (talk) 14:35, 4 September 2015 (UTC)

Heat transfer of a candle in the wind
If I have a flame with a pot over it, how does a little bit of wind blowing affect the heat transfer? --Yppieyei (talk) 15:02, 4 September 2015 (UTC)


 * Convection. -- Jayron 32 15:09, 4 September 2015 (UTC)


 * ... and the heat transfer can be reduced by 50% in even a very gentle breeze, and reduced by more than 90% in a significant wind (depending, of course, on the positioning of the pot and the amount of shielding, and assuming that the flame is not blown out).   D b f i r s   15:20, 4 September 2015 (UTC)


 * And to keep it from blowing out, we have the hurricane lamp. StuRat (talk) 17:46, 4 September 2015 (UTC)


 * Good luck cooking on one. 64.235.97.146 (talk) 18:21, 4 September 2015 (UTC)


 * Well, with a hurricane lamp that's open at the top, the heat transfer to a pot placed on top should be reasonably efficient (provided you leave enough of a gap to allow air flow so the flame doesn't go out). The problem is the small flame.  Nobody is going to cook a turkey with that flame, but maybe you could melt some chocolate to pour over your ice cream (or butter for your popcorn). StuRat (talk) 18:33, 4 September 2015 (UTC)
 * A pot over a candle is, in effect, a very small and inefficient Portable stove. Blog posts suggest that three candle flames can heat a standard size can of soup or similar types of prepared foods in about 30 minutes under optimal conditions, namely no wind and ambient room temperature. A Tea light is a small flat candle enclosed in a thin metal can, which can be used to keep a teapot warm, though not to prepare tea. They are usually used with a basic wind enclosure as even mild indoor breezes will have an adverse effect on their performance. Ultralight backpacking stoves need to be operated in more adverse conditions such as winds and lower ambient temperatures. They use a variety of fuels with considerably higher heat output than candles. Sterno or jellied alcohol is one step up from the common candle. Users of these stoves know that shielding the flame from the wind is essential, and there is extensive discussion of wind shields in sources devoted to backpacking and mountaineering. Here is an example and a Google search will yield many more. Cullen328  Let's discuss it  06:19, 6 September 2015 (UTC)

Colorado hawk-like/songbird-like bird call
Moved by me from the WP:RDM section of the same name. Nyttend (talk) 21:55, 4 September 2015 (UTC)

I'm currently in Littleton, a suburb of Denver, Colorado. Throughout the day, I've been hearing a call I've never heard before: a strong, but smooth whistle, one note (one pitch), that whistles three times in a row, slowly, over about 2 seconds. I thought it was some new little bird until I heard it do a hawk-like screech/scream. But mainly, it goes around doing the whistling. I've been to the list at and listened to every bird there at the Cornell Lab website, and none come even close. I then tried the European starling just in case, but I've never heard that bird make this smooth whistled tone before (which carries quite a distance, by the way, as the bird keeps moving). Any ideas from anyone else would be most welcome! Reflectionsinglass (talk) 20:04, 4 September 2015 (UTC)


 * Have you tried listening to the Screech owls here ?. I'd call it more of a trill than a whistle, but it does a monotonic call, as well as its eponymous crying screech. Usually they are more vocal at night, but I've heard them in the evening and late morning as well. SemanticMantis (talk) 22:06, 4 September 2015 (UTC)


 * If you haven't actually seen the bird, it seems possible you might be hearing prairie dogs. They have a variety of calls, and some of them sound like that description, particularly the hawk alarm call.  And they definitely live in that area. Looie496 (talk) 15:16, 7 September 2015 (UTC)