Wikipedia:Reference desk/Archives/Science/2015 October 11

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October 11

science (carbon quadruple bond)

is carbon make quadrant bond (4 bond),if yes, then what is machenism. how may this be possible? — Preceding unsigned comment added by Shahjad ansari (talk • contribs) 06:31, 11 October 2015 (UTC)

That was a good question! I was sure the answer would be no, but then I looked up quadruple bond and found this. So yes, all four sp3 orbitals in carbon can bond to a second carbon; the fourth bond is stronger than a hydrogen bond, though clearly not the preferred interaction. Wnt (talk) 06:42, 11 October 2015 (UTC)

See also the question Bonding in C₂, a carbon-carbon quadruple bond? on Chemistry StackExchange. There is no clear answer known. – b_jonas 09:53, 16 October 2015 (UTC)

electron

may elecron be destroyed ,if yes then how thir may possible? — Preceding unsigned comment added by Shahjad ansari (talk • contribs) 06:34, 11 October 2015 (UTC)

According to a paper cited in electron,[1] electron decay should not occur within 10²⁶ years. Electrons can be 'destroyed' by annihilation with a positron, the antiparticle of the electron. Wnt (talk) 06:45, 11 October 2015 (UTC)

See also electron capture: a process in which the proton-rich nucleus of an electrically neutral atom absorbs an inner atomic electron, usually from the K or L electron shell. This process thereby changes a nuclear proton to a neutron and simultaneously causes the emission of an electron neutrino.

p+

+

e−

→

n0

+

ν e

-- ToE 12:13, 11 October 2015 (UTC)

The issue that frequently comes up when talking about this kind of thing is that "destroy" is a very general word that lacks scientific precision. You can "destroy" an electron in the sense that you no longer have an electron, but you can't "destroy" mass-energy, in the sense of causing it to no longer exist; it just changes form. And equivalently you can "create" electrons by transforming other things into them. Similarly, we often talk about "destroying" macroscopic objects, like a book, but again, nothing ceases to exist. If you burn paper, you simply transform it into other substances through chemical reactions. As long as you capture all the products of the reaction, you could turn them back into the paper with energy, time, and precise enough tools, like nanomachines. See Maxwell's demon for a somewhat related concept. --71.119.131.184 (talk) 21:28, 12 October 2015 (UTC)

astronmy

if earth are bind with the gravitation field of sun then what make the sun to bind in its orbit? — Preceding unsigned comment added by Shahjad ansari (talk • contribs) 06:37, 11 October 2015 (UTC)

You should try to make your question clearer. I think you are referring to the Sun's galactocentric orbit in the Milky Way? This is due to the combined gravity of the stars of the galaxy (in which the central black hole plays only a small part) plus a large component of dark matter whose nature is unknown. Wnt (talk) 06:48, 11 October 2015 (UTC)

All things considered, Gravity is actually a very weak force, it is by far the weakest of the fundamental forces. However, even though it is very weak, it can act over immense distances, in fact there is no limit to the distance it can act. So even though you can jump off the ground despite the gravity of the entire mass of the earth acting on you, if you were floating in space as far away as the moon, but NOT in an orbit around the earth, you would eventually fall to the earth. Vespine (talk) 23:07, 11 October 2015 (UTC)

Management postgraduate degrees

duplicate
The following discussion has been closed. Please do not modify it.
There's many management postgrad degrees whether business management, project management, operations management but are they worth it? If you can get a job in those areas without it, is experience valued more than a postgrad degree? Will it make any difference to long term progression in your career? 2A02:C7D:B91D:2200:6094:AAC9:8C83:4FDE (talk) 20:08, 11 October 2015 (UTC)

You have more or less just asked the same question above Wikipedia:Reference_desk/Science#Engineering_and_operations. Please don't re-post like this.--Aspro (talk) 22:21, 11 October 2015 (UTC)

Weight loss by lowering the average temperature

How much body weight could a person expect to lose when moving into an environment that is consistently 5C cooler than what he has been accustomed to given that he eats the same type and amount of food?--213.205.252.131 (talk) 21:46, 11 October 2015 (UTC)

I'll be surprised if there is a good answer to this question. Put on a jumper and there's no difference ;) We know people burn more calories in colder climates, but metabolism and rate of activity also changes, as does regular clothing. Secondly, the difference between 18c and 13c would have much more of an effect than the difference between 25c and 20c. Vespine (talk) 23:19, 11 October 2015 (UTC)

Lots of good info here from a course in medical physics. I think the answer could be worked out from the info given there. Shock Brigade Harvester Boris (talk) 23:33, 11 October 2015 (UTC)

OP:OK lets be more specific: temperature reduces from 24C to 19C.--213.205.252.131 (talk) 00:01, 12 October 2015 (UTC)

What kind of answer do you expect? A specific weight? like 5kg? 2kg? I don't believe anyone will be able to give you any kind of reasonable answer, even with the above refernced calculations. The MOST you could work out with the quite complicated calculations is how many more calories you will burn in the colder environment. That STILL doesn't come close to answering how much weight you would eventually lose. Theoretially if you burn more calories than you consume, you will eventually wither away and die, but the skinnier you get the less you burn, so if you reduce your calorie intake just a little eventually you probably hit a balance, but there are many factors here too, exercise, sleep, basal metabolic rate which will vary the result between individuals considerably. Also, "eating the same amount of the same food" is a lot easier said than done, unless you religiously monitor your calorie intake, eating a few hundred calories a day is extremely easy to do even inadvertently. Vespine (talk) 02:34, 12 October 2015 (UTC)

If there was a correlation between weight loss and environmental temperatures, we should see a correlation in population data. There is none. Obesity is the norm in the deep south of the United States. Obesity is the norm in the Great Lakes of the United States. Obesity is the norm throughout the Midwest of the United States. Obesity is the norm in the hot and humid Hawaiian islands. Obesity is the norm in the frigid Alaskan shores. So, data shows that there is no correlation. Therefore, you shouldn't expect to discover one. 199.15.144.250 (talk) 13:08, 12 October 2015 (UTC)

Diet seems to be the issue. Have you ever seen a fat Vegan? ←Baseball Bugs ^{What's up, Doc?} carrots→ 21:41, 12 October 2015 (UTC)

Yes - many. Vegans are more common in Asia, and they can be very fat. Eating a diet high in carbohydrates and sugars is unhealthy with or without meat added to it. The primary reason that people think vegans don't get fat is because most people who consume terrible diets are willing to eat anything that doesn't move (and many things that do). It isn't as common for a person to choose to be a vegan and still consume enough calories every day to maintain a large elephant. 75.139.70.50 (talk) 21:50, 12 October 2015 (UTC)

If there was a correlation between weight loss and environmental temperatures. But this ignores one major premise of the OP, that they still eat exactly the same amount and type of food. IF you could ALSO show that the fat people of the south eat EXACTLY the same amount of food as the fat people in the north, then your contention would be valid, however I see no reason to assume that's the case. It could very well be the case that the people of the north have to eat a little bit more, and come to think of it, they could wear a few more clothes and have better insulated houses with more heating. THAT I think outweighs any effect of temperature difference. Vespine (talk) 22:14, 12 October 2015 (UTC)

The main problem is sweating. If you generate more heat than convection and conduction can remove, sweat takes care of the excess. If the temperature drops, you won't produce more heat, you'll sweat less. 19°C - 24°C is probably the region in which your body would switch between sweating and using more energy: 19° in rest may be a bit chilly, 24° while active is quite warm. Can't see a way to estimate that, maybe there are studies that have measured such a thing... Ssscienccce (talk) 22:14, 14 October 2015 (UTC)