Science desk
< June 26	<< May \| June \| Jul >>	June 28 >

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.

June 27

Cell division

Describe about cell division -- Ganga Basnet (talk · contribs)

Have you read our article Cell division? If that does not answer your question, can you be more specific about what you want to know? --Lambiam 07:24, 27 June 2020 (UTC)[reply]

Do your own home work?

Chemistry

If all kinds of matter is made up of atoms, including biotic and abiotic substances. Then living organisms and non-living substances must have been made up of same atoms. like biotic organisms are made mostly up of carbon molecules,and on the other hand coal is made up of the samecarbon molecules. Then why there is a difference between living organisms and non-living substances? -- 117.209.175.248 (talk · contribs)

Read Life for some possible insight. ←Baseball Bugs ^{What's up, Doc?} carrots→ 14:10, 27 June 2020 (UTC)[reply]

The simple answer is that it all depends on how these atoms are arranged, first into molecules, and then how these molecules are connected and interact, not only chemically but also mechanically. A cooking pot and a vacuum cleaner are made up from the same kind of atoms, but you cannot use a cooking pot for vacuuming or a vacuum cleaner for cooking. A vacuum cleaner is much more complex than a cooking pot; it is composed of a collection of components that have to be combined and connected in specific ways for the vacuum cleaner to function. But both cannot function without an external source of energy; heat for the cooking pot and electricity for the vacuum cleaner. Living organisms are much more complex than vacuum cleaners, but they too consist of a collection of components that have to be combined and connected in specific ways for the organism to function. And then they too need a source of energy. --Lambiam 14:39, 27 June 2020 (UTC)[reply]

It is not correct that "biotic organisms are made mostly up of carbon molecules". They (we) are made of molecules most of which contain carbon. For a simple example, glucose has the formula C₆H₁₂O₆, meaning that each molecule contains 6 carbon atoms, 12 hydrogen atoms, and 6 oxygen atoms. To be glucose rather than some isomer of it, the atoms also have to be arranged in a specific way. If a substance contains only carbon atoms, then it's coal or graphite or diamond or a fullerene, depending on how the atoms are arranged. --76.71.5.208 (talk) 21:56, 27 June 2020 (UTC)[reply]

Most molecules the human body do not contain carbon. — Preceding unsigned comment added by 2a01:e34:ef5e:4640:30b5:433d:905b:548b (talk) 11:00, 28 June 2020 (UTC)[reply]

True, see Composition of the human body. The vast majority (> 98.7%) are water molecules. --Lambiam 12:30, 28 June 2020 (UTC)[reply]

Weber vs. tesla vs. ampere/meter

What are the practical (i.e., explained in a way, if possible, without relying solely on mathematical statements) differences between these units? Specifically, what are the physical effects, on objects in a magnetic field (including the object generating the field), of changing the value of any one of these units? ZFT (talk) 20:48, 27 June 2020 (UTC)[reply]

As a start, let's look at Weber (unit): "In physics, the weber (/ˈveɪb-, ˈwɛb.ər/ VAY-, WEH-bər; symbol: Wb) is the SI derived unit of magnetic flux. A flux density of one Wb/m² (one weber per square metre) is one tesla." (refs omitted) So a weber is a total amount and a tesla is how concentrated or intense it is in a given area. That's like you can stand your whole weight on a bed of needles because your weight is spread over a large area (not much pressure on any one needle) but if you concentrate that same weight focused by standing on a single needle, yeeeeouch! Or if one nail can only hold up a certain-weight object on your wall, you can get more total weight held by using more nails. DMacks (talk) 21:26, 27 June 2020 (UTC)[reply]

The difference between the tesla and ampere/metre is not so easily explained, even though they have (for historical reasons) quite different dimensions. The first is a unit for the strength (flux density) of the magnetic B-field, the other for the strength (but now force per unit of flux) of the H-field. See the section Definitions, units, and measurement of our Magnetic field article. --Lambiam 08:10, 28 June 2020 (UTC)[reply]