Recent comments in /f/askscience

CrustalTrudger t1_j5t7j9q wrote

Reply to comment by d49s00 in Can sedimentary rock for on land? by 24_Elsinore

> For accommodation space to be created in the continental realm, the continental part of a tectonic plate needs to break apart, known as a rift basin.

While it's true that continental rifts are definitely locations where accommodation space is made, it's demonstrably false that these are the only continental environments where accommodation space is made either in the geologic past or in the modern. To start, there are several other tectonic environments where tectonic components of subsidence generate (many times very significant) amounts of accommodation space. The largest by far would be in convergent environments where loads associated with the growth of large mountains and/or negative buoyancy from underthrust lithosphere generates significant subsidence and thus accommodation space. Any region with mountain ranges still experiencing active convergence (e.g., Himalaya, Andes, Greater Caucasus, Taiwan, etc) will largely also be actively generating tectonic subsidence in portions of their respective foreland basins and thus actively generating accommodation space.

Other tectonic environments can also generate subsidence and accommodation space, though they tend to be more localized. For example releasing or transtensional step-overs in strike slip systems tend to also produce large amounts of (very localized) subsidence and thus accommodation space. Ridge Basin in southern California is a classic example of this type of environment (though no longer actively forming accommodation space), but there are many releasing step overs and transtensional bends in large, modern continental strike slip systems (e.g., along the San Andreas, North and East Anatolian, Altyn Tagh, etc.)

Outside of tectonic sources of subsidence, sediment deposition tends to beget more sediment deposition because the deposited mass (1) induces flexure of the lithosphere - generating accommodation space and (2) induces compaction / dewatering of underlying sediments - generating accommodation space. Additionally, in environments with large amounts of organic material incorporated into deposits (e.g., marshes, wetlands, etc.), organic decomposition can lead to large amounts of subsidence. Thus, many coastal environments, especially those adjacent to large deltas (which represent massive amounts of sediment being deposited) experience significant subsidence and accommodation space generation. As an example of this, consider the gulf coast of the US and its rapid subsidence. This is in no small part due to the combined effects of (1) continued subsidence from the mass of the Mississippi delta, (2) subsidence of compaction and organic decomposition, and (3) large scale levee systems keeping the Mississippi along its current course and thereby preventing sediment deposition in the adjacent areas. I.e., in part the elevation of the gulf coast is actively lowering because accommodation space is being generated but virtually no sediment is allowed to fill it through artificial means.

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GotTheNameIWanted t1_j5t29eh wrote

Reply to If I had two cups of water, one normal size and one as big as a swimming pool and stirred them both with proportionally sized spoons, would the larger pool of water keep spiraling longer than the smaller? by r3volc

Yes.

Think of it this way, it would require more energy to move that larger spoon compared to the smaller spoon. This energy is stored in the waters movement once you stop stirring as kinetic energy. More input (i.e. larger spoon) would mean more kinetic energy.

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Lankpants t1_j5t28t9 wrote

Reply to comment by AlienTD5 in If I had two cups of water, one normal size and one as big as a swimming pool and stirred them both with proportionally sized spoons, would the larger pool of water keep spiraling longer than the smaller? by r3volc

In addition to what the other commenters have said there's also another effect at play. To get the pool spinning at the same RPM as the cup the outside needs to be moving several times faster. If both swirl once per second then the water at the edge of the pool needs to be covering the entire radius of the whirlpool every second.

What this means in practice is that if the two are spinning at a similar speed the energy even of one water molecule in the pool on average is higher. There are also more molecules moving. So the pool has far more energy. And remember, water is a liquid. The partials behave relatively independently and experience friction with the wall independently. So any of these particles at the edge of the pool have more energy to lose to friction. There's also a lower percentage of particles experiencing direct friction with the wall at any given time due to the square cube rule.

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Slappy_McJones t1_j5szpoe wrote

Reply to Why does hot air cool? by AspGuy25

If you are scanning through a port window, it might be a reflectivity issue, like others have stated. Pop-open the chamber door (briefly) and take a scan or cross-check with a quick responding contact thermocouple probe.

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sentientskeleton t1_j5siqen wrote

Reply to comment by bildramer in If I had two cups of water, one normal size and one as big as a swimming pool and stirred them both with proportionally sized spoons, would the larger pool of water keep spiraling longer than the smaller? by r3volc

The only thing that will make the water stop spinning (reduce its total angular momentum) is drag from the walls, so you can't ignore it, no matter how large the Reynolds number. Even at high Re you can't completely ignore viscosity either, its effects only get concentrated into very thin regions (like boundary layers) but there it is extremely important.

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rankedscalper t1_j5sikni wrote

Reply to Why does hot air cool? by AspGuy25

They way I think about it, is that it loses energy density and gains electrons. There’s someone known as Renzo who did plasma electrolysis and synthesized oxygen from sulphur at low current on YouTube. I think that usually we describe this as solely an electron exchange but that the electron configuration can be broken down by photo-disintegration and measured by decay of any atom into helium concentrations. Imagine electron configurations with like 2[He] and think about an electron shell being a cloud of probability with resistance being relative to the radiant energy. Radiant energy is primarily responsible for black holes

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colcob t1_j5sdytd wrote

Reply to comment by Old_comfy_shoes in If I had two cups of water, one normal size and one as big as a swimming pool and stirred them both with proportionally sized spoons, would the larger pool of water keep spiraling longer than the smaller? by r3volc

So by rotational rate i mean the angular velocity, ie. degrees per second, RPM, not the tangential velocity.

I guess I would stir a cup of about 1 revolution per second, so I'm imagining that if you stir the swimming pool cup at 1 revolution per second, the water's going pretty damn fast at the edge!

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