Wikipedia:Reference desk/Archives/Science/2015 October 26

= October 26 =

Do great apes have senses of humour?
(Besides modern humans, obviously.) --Romanophile (talk) 05:41, 26 October 2015 (UTC)


 * Dr Marina Davila-Ross certainly seems to think so. Vespine (talk) 05:54, 26 October 2015 (UTC)


 * From Koko "Koko has also been reported to use language deceptively, and to use counterfactual statements for humorous effects, suggesting an underlying theory of other minds.[18]" with reference. -- Jayron 32 15:13, 26 October 2015 (UTC)


 * I would expect that most types of humor, like puns, would be impossible for other great apes to understand. Slapstick might work on them, though, like slipping on a banana peel.  And perhaps hiding something so somebody looking for it can't find it might qualify as humor to them.  Schadenfreude is another possibility.  I can picture a great ape being amused by another that is too fat to climb a tree.  StuRat (talk) 00:00, 28 October 2015 (UTC)


 * Of course they do. I believe there was even talk of this chimp replacing Letterman. Unfortunately he struggled to learn English to a sufficent standard. Hillbillyholiday talk 00:16, 28 October 2015 (UTC)


 * I'm pretty sure my dog has a sense of humor - it would be really surprising if the great apes did not. SteveBaker (talk) 15:52, 28 October 2015 (UTC)


 * • If we can believe YouTube videos of Koko, she liked Robin Williams  and also liked being tickled. Whether this can be extended to "having a sense of humour"? I don't know.
 * Off topic, but another video alleged to show that another gorilla (Quiqley) had been 'taught' the concept of death, and understood that he would die. He was not enthusiastic about the idea. I'm now fairly sure certain that was a hoax. However, this in the NY Times makes interesting reading.
 * • Back on topic, Do animals have a sense of humour? from Slate via New Scientist, seems relevant. Koko gets a mention,:
 * "...once tied her trainer’s shoelaces together and signed “chase”.
 * • That sounds like humour (and slapstick) to me! (IANAP-I Am Not A Primatologist) - 220  of  Borg 10:17, 29 October 2015 (UTC)

DHT and activities.
Do testosterone boosting activities like masturbation and anaerobic exercises like intense weight lifting and pushups etc... increase DHT and accelerate hair loss ? Does Minoxidil 5% in such a case block DHT at the follicles or become helpless ? What about Finasteride 1mg ? Does it become helpless if testosterone is too high ? — Preceding unsigned comment added by 175.101.24.136 (talk) 13:02, 26 October 2015 (UTC)
 * We do have the articles Dimoxinil and Finasteride. The first works by increasing the growth of blood vessels, not by counteracting DHT directly.  The second has hormonal effects not limited to the scalp. μηδείς (talk) 16:41, 26 October 2015 (UTC)

Watertighting wheel wells of amphibious cars
How is there a watertight seal between the wheel wells and the drive shaft while still allowing the axle to spin in most amphibious automobiles? 20.137.7.64 (talk) 13:22, 26 October 2015 (UTC)
 * Stuffing_box 196.213.35.146 (talk) 14:00, 26 October 2015 (UTC)

Automobiles have many rotating seals that inhibit leakage of water e.g. at the coolant pump, or of oil from the crankshaft bearing. Instead of a stuffing box filled with string, seals now often use O-rings and elastomer materials as noted in the article Radial shaft seal. The amphibious cars shown have at their rear a drive shaft with seal for a propeller (the Schwimmwagen lacks reverse propulsion and can reverse only slowly by spinning its land tyres). Bestfaith (talk) 19:50, 26 October 2015 (UTC)
 * There was also the DUKW, a military issue amphibious vehicles which have been repurposed in many cities to give Duck tours. -- Jayron 32 21:37, 26 October 2015 (UTC)


 * Am puzzled by the above explanations. If you look at the right hand image. The drive shaft joins the gearbox above . The water line. Thus one doesn’t need a seal. Seals course friction and lower the milage per gallon. OK perhaps, in military vehicles, because the tax payer pays, but for a civilian vehicles ! They were designed so that water didn't ingress into the floor pan (via foot pedals, gear lever etc.) by making sure these ports where 'above' the water line.--Aspro (talk) 20:55, 27 October 2015 (UTC)
 * The Amphicar transmission has a rear-mounted hypoid differential and 4-speed gearbox built by Porsche (shown here) that are filled with oil, and so require rotating seals regardless of possible use in water. Drive to the twin three-blade screws is taken through a separate water transmission controlled by a transfer lever with forward and reverse positions, located next to the conventional gearshift on the center console. Special seals around the doors and their hinges contribute to keeping the footwell dry below the water line. Bestfaith (talk) 18:55, 28 October 2015 (UTC)


 * Note: The vehicles you see here were built at a time where heavy duty cylindrical roller bearings were used and serviced with the grease gun and greases were grease and not least molybdenum disulfide based lubricates. Todays wheel bearings made dual ball bearings, made for replacement after a mileage or shock force failure not to be serviced itselfes, complte assembled and lubricated with molybdenum disulfide (MOS2) based lubricates and graphite to prevent lubrication failures causing accidents. -- Hans Haase (有问题吗) 22:20, 30 October 2015 (UTC)


 * Think that was just a complicated way of pointing out that we now used sealed bearing.--Aspro (talk) 23:03, 30 October 2015 (UTC)

Horse vs Bicycle
Who would win in a 50 mile race; a man on a bicycle or a man on a horse? 202.20.99.196 (talk) 16:21, 26 October 2015 (UTC)


 * See Man versus Horse Marathon, which has both on foot, and which sometimes the man wins. Given the greater speeds of a bicycle, the man on the bike would win 100% of the time, even if not a professional-class racer.  Horses cannot keep full speed for more than a few miles, so over 50 miles, the man in the bike should win always.  -- Jayron 32 16:49, 26 October 2015 (UTC)


 * Might depend a bit on the track. Something somewhat rough and narrow may favor a horse more, but I certainly agree with your assessment if the roads are paved (although I don't think it would be safe for the horse to run 50 miles over pavement).
 * Century_rides for cyclists on paved roads can usually be done in under 12 hours by most people fit enough to attempt the task. Obviously dirt trails would be slower. Average time for the 100 mile Tevis_Cup is a little under 14 hours. These are both 100 mile races but perhaps over a 50 mile length the horse's lack of endurance may be less of an issue than in a 100 mile race. So maybe a very good horse could beat a merely decent cyclist for some 50 mile journeys. SemanticMantis (talk) 16:58, 26 October 2015 (UTC)


 * Note that per the article, the Man versus Horse Marathon had a female champion cyclist lose to the horse in 1985. However the first victory to a human was to a cyclist by over 3 minutes in 1989. The article doesn't seem have other details of cyclists competing. These is some additional discussion in the article talk page suggesting a big reason for the failure of cyclists to win until 1989 was due to the lack of cyclists experienced in that type of terrain competing. Of course, the distance is a lot shorter than 50 miles, still I agree with SemanticMantis and wouldn't be sure that a non professional will always win depeding on the type of terrain. BTW, Endurance riding suggests 50 miles is a common distance for such horse racing, so if you'll look around you'll probably find completion times for such distances. However times are likely to depend significantly on the terrain so it'll probably be difficult to compare them to human times over such distances. Nil Einne (talk) 17:59, 26 October 2015 (UTC)


 * Everyone seems to have assumed the Q is about a champion bike racer. What happens when we put an average man on the bike, instead ? StuRat (talk) 22:02, 26 October 2015 (UTC)
 * Well, it depends on whether the couch potato brought along his handgun. Wnt (talk) 14:11, 28 October 2015 (UTC)
 * No, I mentioned 12 hours for century is the common goal for people who think themselves fit enough to attempt it, that's not an estimate for champion racers - a recent record for 100 miles cycling was set in 2003 at 3hr 23min 33sec . Likewise, many if not most horses cannot travel 100 miles at high speed. What's an "average man" anyway? Maybe you can try a century ride and let us know your time. Maybe I'll do it too, and we'll have an average for n=2 :) SemanticMantis (talk) 22:23, 26 October 2015 (UTC)
 * Yeah and I specifically mentioned, "wouldn't be sure that a non professional will always win depeding on the type of terrain". Which was of course in response to what you said, and also what Jayron said "even if not a professional-class racer". So it doesn't seem anyone who responded assumed the question was about a champion bike race.... As for average, we need to assume median rather than mean here, since mean makes little sense. Although I know the traditional stereotype of people from China is that they all cycle, when we consider all the people from Africa and Asia (the later particularly China and India) who make up a big percentage of the world's population, I wouldn't be surprised if the median person has never cycled before (remembering also that quite a big percentage of the world's population is fairly young). So if you were to put them on a bike you get something like this . Speaking personally, I cycle to shops around my neighbourhood (perhaps 2 km or so distance tops) sometimes, and have perhaps 10 times over the past 10 years gone further afield (10-20 km) but I'm not particularly fit and don't fancy my ability to make a 50 mile ride in one day (let alone a Century). However if I bring enough food, water and supplies (which will slow me down more but still) I guess I could make it within a few days (perhaps longer depending on the terrain). Probably the biggest barrier is I'm still not that good at fixing many problems that may arise with my bike, and I'm not sure I'll be that good at finding some place safe to sleep. But I definitely don't fancy myself making it there ever given my current ability, on a horse.  I suspect you'll find the same for the median person, since while I'm not totally certain the median person has never cycled, I am sure they've never riden a horse. In other words, the average person on a bike will surely either beat the average person on a horse or it will be a tie since neither of them make it to 50 miles. Doesn't seem particularly meaningful though.... Now technically the OP mentioned "man" not human, so perhaps they only mean adult males. This would if anything seem to push the trend in favour of the bicycle.  Either way, it makes sense to restrict ourselves to people with some level of ability on either. This is what I was doing, it sounds like what SemanticMantis was doing and I think was what Jayron32 was doing. This doesn't mean they have to be champions on either, but probably means at a minimum they have to be able to make it 50 miles without either killing themselves or the horse.  Possibly it's easier to train someone to be able to successfully ride a horse 50 miles than it is to train them to ride a bicycle 50 miles, since the horse will be doing a lot of the work (although as SemanticMantis said, why average person but not average horse?), but I'm not sure. After all, a lot of people are going to be very uncomfortable riding the horse since they just don't trust it, and it'll get even worse if the terrain is challenging. And most races over that distance seem to involve vet checks. While this may be mostly for humane reasons, it still implies the need for the rider to have some understanding of the horse. I guess if they aim for 2 or even 3 days, they may be a bit better off.  Nil Einne (talk) 07:57, 27 October 2015 (UTC)


 * If the ground is not ideal or bikes, such as damp, marshy or muddy dirt,or having to leap over fences, hedges and ditches, or swim across deep but slow-moving creeks the horse would be at a great advantage.I have ridden a horse across a creek when the horse was swimming, and I was not much of a rider. I could not have waded the creek carrying a bike. In wartime, cavalry often crossed 50 mile stretches which would have been a nightmare for bicyclists. Edison (talk) 03:50, 27 October 2015 (UTC)


 * You can always design a course that will favor one over the other. Consider this: "Which is faster, a racehorse or a snail?"  Well, if the first hurdle on the track is a 50 foot high, foot-thick wall with a row of 2" tall holes at the base - then the snail will definitely win.  Does that make it "faster"?  Even if you're talking about an absolutely flat, uniform running track - then the winner depends on the distance over which the event is run, the temperature and probably a whole bunch of other stuff. SteveBaker (talk) 15:51, 28 October 2015 (UTC)

Grounding
If I put both positive and negative points of battery to a bulb it will work. But if I put bulb's one point, the one that should be with battery's -ve, and the battery's -ve to earth I don't think it will light up. Why? 124.253.251.169 (talk) 17:02, 26 October 2015 (UTC)
 * The reason is works with a plug is that they connect the generator to the ground. If they didn't then you would not get a shock when you touched a plug. (Which sounds pretty nice, but there are historical reasons making that impossible.) If you go out and check you will find wires down the sides of telephone poles that connect the ground to the transformer up on top. Also every house has a connection to the ground. So when you get a shock power flows through you, into the ground, up one of those wires, then back to the transformer, and finally the generator. If you wanted you could do the same with the battery - connect one side to the ground, and see if you can get power to flow through the ground and light the bulb (it might be tough because of the low voltage, wet earth will be easier). Ariel. (talk) 18:06, 26 October 2015 (UTC)


 * Do I understand this correctly? You have connected one side of the bulb to battery positive. The other side of the bulb and battery negative are connected to two different earth connections, right? How good are your earth connections? Are you even talking about the soil, or something commonly referred to as 'earth' such as a vehicle body? Do you mean the earth wiring of a dwelling? If the latter, I suggest that you immediately stop testing and have the house wiring checked by a competent certified electrician, as it seems there is a discontinuity in the house's earth wiring that is hazardous to human life. Please be more specific. Akld guy (talk) 01:50, 27 October 2015 (UTC)


 * Some personal experience/original research: When installing ground rods at transformers it was straightforward in my locale to achieve a ground impedance of under 10 ohms via a 10 to 30 foot driven ground. So draw your circuit with the bulb connected to "ground" through a 10 ohm impedance and a battery terminal also connected to the same ground through 10 a ohm impedance. This is similar to a 20 ohm resistor connecting the bulb to the battery, with a wire connection of the other bulb terminal to the battery. Work out the voltage across the bulb and the current through it. If the bulb does not light, then you could increase the battery voltage, or select a different bulb, or decrease the ground impedance in two ways: drive the ground rod deeper, or add more ground rods  several feet away from the initial ones and electrically connected to them. Four 10 ohm grounds located 6 feet apart and bonded together typically gave a 2.5 ohm combined ground impedance. I found that there might also be a slight stray voltage, both AC and DC, between the ground rods, as a complication to the thought experiment. Do not try this in real life without a utility locate process to make sure there are no buried lines or pipes where you drive ground rods.Edison (talk) 03:41, 27 October 2015 (UTC)


 * Resistance is discussed at length in electrical ground. Some specialty systems like Counterpoise (ground system) are used when it is high; of course, in your example, that basically means having two nets of wires that touch each other, or come close.  The notion of perfectly zero ground is an approximation; that's often OK though, because the potential of the battery or AC connection is often kind of up in the air also, and it's only the difference that matters, so there's no need to have one better than the other.  The question here is whether the ground resistance is comparable to the resistance of your lightbulb; resistors in series is relevant.  A key thing to remember (though I think you know this) is that electrons aren't coming out of a battery unless they're also coming in, because even a tiny excess would create enormous voltages to drive them away. Wnt (talk) 14:06, 28 October 2015 (UTC)