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August 19

Swimming pool water

Dear RefDeskers. Having recently been to the swimming pool more often than not, I came upon this riddle.

Say we have an indoor pool of water, for simplicity, rectangular or square, regular, of a known width, breadth and depth, filled with regular water or any other liquid that might be suitable for the thought experiment. The pool is lined with tiles or any other impermeable material. For simplicity, we assume there are no water inlets or outlets or anything that might disturb the volume of the liquid. All other conditions (temperature, air pressure, etc.) standard. Now, we have some people splash around and then exit the pool. Given all the data above, and assuming that we can reasonably know any other measureable factors, is there a calculation that would allow us to determine how long it would take for the water to completely calm down and form an even surface, say, with a tolerance to +/ - 20 mm, +/ - 10 mm, +/ - 1 mm? Ouro (blah blah) 06:23, 19 August 2023 (UTC)[reply]

The kinetic energy of the people splashing in (which can be calculated using measurable data) is transferred to the waves, which will lose the energy by dissipation. I expect that there are well-known scientific laws that relate the energy of the waves to their amplitude and give the rate of dissipation. --Lambiam 11:33, 19 August 2023 (UTC)[reply]

You have to consider the spectrum of the waves and the dimensions of the pool. Shorter waves dissipate faster. At the edges (sides and bottom), you get some non-linearities that can double or triple the frequency of a wave, transferring energy from long waves to short waves. Full hydrodynamics simulations are hard, but can be done reasonably well today. For the amateur researcher, I think an experiment is a lot easier. PiusImpavidus (talk) 10:12, 20 August 2023 (UTC)[reply]

What animals need to feed at least every 12 hours.

If a zoo was unable to feed its animals between Midnight and Noon every Tuesday, what animals would be significantly negatively impacted? I figure it would kill the hummingbirds, but some animals like snakes that are on the other end of the scale (My local park service only feeds the snakes in its exhibit house on one day of the week). Are there any mammals that have to eat that often? (Grazers like cows?) Naraht (talk) 16:09, 19 August 2023 (UTC)[reply]

Mouse? Ruslik_Zero 16:24, 19 August 2023 (UTC)[reply]

Shrew, probably. {The poster formerly known as 87.81.230.195} 51.198.140.169 (talk) 17:53, 19 August 2023 (UTC)[reply]

Here’s the guideline for zoo animal feeding in India. They might feed large carnivores ground meat daily, but they give them large bones or rabbits weekly to maintain teeth and jaw muscles. There might be concern of large aggressive carnivores turning cannibal if they get as hungry as they do in nature, days after the last feeding. Nursing mother carnivores might be fed daily but other large carnivores in nature may eat big meals days apart. Baby animals and recently hatched animals need frequent nutrition. As noted, reptiles might go days without feeding. https://www.ndvsu.org/images/StudyMaterials/Nutrition/Feeding-Schedule-Wild-Zoo-animals.pdf Edison (talk) 18:33, 19 August 2023 (UTC)[reply]

An animal can eat more often than the zoo feeds it, as some food can be stored in the animal's enclosure. Hummingbirds consume nectar regularly from flowers, artificial or natural. The artificial flowers get refilled once a day, the natural flowers get cared for like any other plant. Grazers can eat the grass growing in their enclosure. If there's enough grass per grazer (unlikely), the zoo doesn't have to feed them at all. PiusImpavidus (talk) 10:33, 20 August 2023 (UTC)[reply]

An acre (a square 208 point something feet wide) is apparently enough for 2 sheep without keeping them in a revolving subset of that acre in which case an acre can feed a lot more. Sagittarian Milky Way (talk) 12:22, 20 August 2023 (UTC)[reply]

The usual way to envisage an acre is a furlong by a chain, or 220ˣ × 22ˣ. For those who can't understand the units: 660 by 66 feet (201 m × 20 m). I'd wonder about the asserton that an acre could feed two sheep though, are we talking about an acre of sweet, lush lowland grass, or an acre of high moorland? Martin of Sheffield (talk) 14:18, 20 August 2023 (UTC)[reply]

Or, a standard US football field (not including end-zones) is almost exactly one acre -- 1.094 acres to be precise. 136.54.106.120 (talk) 19:09, 20 August 2023 (UTC)[reply]

"a good rule of thumb is 10 ewes and 15 lambs per acre of pasture. This assumes that you will be using a well-executed rotational grazing regimen" DuncanHill (talk) 14:31, 20 August 2023 (UTC)[reply]

Because that was the shape of the pre shape-agnostic acre cause their plow animals could only sustain about 10 chains between rests and that was a convenient shape (less plow-turning but not inconveniently skinny). I'm a New Yorker so I think of an acre as a Twin Tower footprint or the end of a skinny Manhattan-style block (enough lots to be 200x200 (8 pairs, 10 pairs in Manhattan). There's also lots of 100x100 buildings i.e. many 1-story supermarkets. Most Chicago blocks are 1 furlong square with a bisecting alley so an acre's exactly 20% the land between road centerlines. When I was there I "obviously" had enough time to walk from the cross-country buses to the lake and back but soon realized their street gaps are bizarre. And that is why I've been to Chicago's core but not Lake Michigan. Sagittarian Milky Way (talk) 00:42, 22 August 2023 (UTC)[reply]

Where would light emitted from a reference frame unaffected by a more complete and comprehensive energy source collapse?

wp:deny

The following discussion has been closed. Please do not modify it.

I was reading and began to wonder where would light emitted from the most bright collapse inside the ocean go for a warmer reflection up to the speed of light? I know that there can even be waves that would go far as to ever really reach an energy output equivalent to the most powerfully massive black hole, but how would this affect the most brightly reflective inertial frame when it even has a difference beyond what would actually ever terminate? Drishithan (talk) 21:38, 19 August 2023 (UTC)[reply]

^{[clarification needed]}

There are at least six places in this query that combine words in ways that make no physical and/or grammatical sense. If this is not a spoof, I suggest, Drishithan, that you find someone with a better command of the English language and grasp of physics to translate it from whatever language you usually speak. {The poster formerly known as 87.81.230.195} 51.198.140.169 (talk) 01:11, 20 August 2023 (UTC)[reply]

I used that query as an AI copilot prompt and had it rephrased for clarity, with the following result:

While reading, I started to ponder where the light emitted from the brightest source would go if it were to reflect off the ocean with enough energy to reach the speed of light. I am aware that there may be waves that could reach an energy output comparable to a massive black hole, but I am curious about the impact on the highly reflective inertial frame beyond its termination point.

Using that as a prompt I asked Perplexity.AI to explain, resulting in:

Based on your question, it seems you are wondering about the impact of highly reflective inertial frames beyond the termination point of light reflected off the ocean with enough energy to reach the speed of light. While the specific scenario you described is not directly addressed in the search results, I can provide some information on inertial frames and the behavior of light in different reference frames.

1. Inertial Frames: An inertial frame is a reference frame in which the motion of a body not subject to forces is always rectilinear and uniform. In an inertial frame, the center of mass of a closed system of interacting bodies is always at rest or in uniform motion^1,3 Any other frame of reference moving uniformly relative to an inertial frame is also considered an inertial frame¹

2. Light Propagation in Inertial Frames: According to the principle of light speed constancy, light propagates at the same speed, denoted as "c," in all inertial frames⁵ This means that the speed of light is independent of the motion of the source or the observer. The distance traveled by light in a given time interval is always the same, regardless of the reference frame⁵

3. Reflection of Light: When light reflects off a surface, such as the ocean, its angle of incidence is equal to its angle of reflection. The reflected light follows the same laws of reflection in all inertial frames⁵

Based on this information, it can be inferred that if light emitted from the brightest source were to reflect off the ocean with enough energy to reach the speed of light, its behavior would follow the laws of reflection in the inertial frame. The highly reflective inertial frame beyond the termination point of the reflected light would experience the same laws of reflection as any other inertial frame. It's important to note that the specific scenario you described involves light reaching the speed of light, which is not possible according to the principles of special relativity. The speed of light in a vacuum is considered the maximum speed in the universe, and objects with mass cannot reach or exceed this speed⁴

Please let me know if there is anything else I can assist you with.

-- 136.54.106.120 (talk) 09:48, 20 August 2023 (UTC)[reply]

Ha ha ha! Oh dear I shouldn't have laughed and me with this pain all down the diodes on my left side ;-) NadVolum (talk) 10:12, 20 August 2023 (UTC)[reply]

Yeah, this is another one of those previews of our future sidelined and observing AI's talking to one-another that is equal parts worrisome in the abstract and yet also reassuring that it clearly isn't going to happen immediately. SnowRise ^{let's rap} 00:45, 21 August 2023 (UTC)[reply]

For info, the OP has been warned for vandalizing someone's User page, and then indefinitely blocked for abuse of editing privileges. {The poster formerly known as 87.81.230.195} 51.198.140.169 (talk) 03:54, 24 August 2023 (UTC)[reply]