Wikipedia:Reference desk/Archives/Science/2024 January 7

= January 7 =

Paddles and air drag
The article for Paddle (spanking) includes a statement that a paddle with holes drilled into it has less air drag than one without holes, and therefore hurts more. Is this actually true? I've definitely heard the statement repeated often in kink circles, and it makes intuitive sense, but has it ever been verified? Or, theoretically/mathematically, how would that work? 2601:401:101:37B0:BC5B:B064:50BF:F5DA (talk) 19:35, 7 January 2024 (UTC)


 * I doubt that this application was what the authors of this study had in mind, but the results seem pretty clear. They tested not only the number of holes but also whether they were concentrated in the centre or near the edges. Mikenorton (talk) 20:47, 7 January 2024 (UTC)
 * Oh wow, this is exactly the kind of thing I was hoping for! Thank you! 2601:401:101:37B0:4C87:1899:C86:3598 (talk) 00:15, 8 January 2024 (UTC)
 * Even if it was the exact same kinetic energy or momentum it'd probably hurt more as pieces of ass bulge into small holes. Not sure why some girls seek a surely higher risk of murder/post-safeword domestic violence to love(?) hole paddling men but whatever. Sagittarian Milky Way (talk) 22:45, 7 January 2024 (UTC)
 * I think you have a few misconceptions about kink, but I shan't get into that here. 2601:401:101:37B0:4C87:1899:C86:3598 (talk) 00:15, 8 January 2024 (UTC)
 * that was disturbing to read. Also, how is Godzilla? Is he safe? Zarnivop (talk) Zarnivop (talk) 00:22, 8 January 2024 (UTC)


 * My mother had a "paddle" for us kids, consisting of a rectangular board from some kids' play set. It had holes in it, and she said that was to raise blisters. (In reality, she hardly ever used it. It was almost a joke.) ←Baseball Bugs What's up, Doc? carrots→ 04:13, 8 January 2024 (UTC)
 * Well, if the paddle had holes in it, then yes, you would theoretically be able to swing it faster, and therefore inflict more pain. However, there's not a great difference between swinging as hard as you can with a paddle with no holes, and swinging as hard as you can with a paddle with holes. There would certainly be a difference, but it would be so miniscule, anybody getting spanked wouldn't feel the difference. Gyatt W Rizz (talk) 15:58, 9 January 2024 (UTC)

Waves of wave unit popularity
What was the most common way to numerically mention different colors of EM and sound waves in different eras? Radio wavelength used to not be less common than frequency right then stations if not bands switched to frequency from wavelength. Why'd they do that? I guess at first they thought in radiator lengths? (multiply by 2 or 4 for simple antennas) but if they switched the numbers would go up in the same direction as music and photon energy. Any other reasons? Was frequency always the most popular for sound? Why not wavelength? All because high frequencies just seem higher? Why is some spectroscopy in normal units like Ångstroms or SI lengths but some is wavenumber? Usually centimeter-gram-second units are old-fashioned but they didn't even switch from waves per centimeter to waves per millimeter even though the numbers would become conveniently-sized. Sagittarian Milky Way (talk) 22:07, 7 January 2024 (UTC)
 * Apparently radio in the UK used wavelength until the 1980s: . Radio dials in the US and elsewhere used "megacycles" from way back: . You might have in mind the switch in the UK to match the rest of the world for easier import and export. --Amble (talk) 22:39, 7 January 2024 (UTC)
 * Were there any 666 stations that didn't avoid mentioning the numerical coincidence? Maybe a cartoon devil mascot or something? It's divisible by 9 so there were some 666 kilohertz AMs. In North America regular radios only get stations divisible by 10 or 200 kHz. Sagittarian Milky Way (talk) 23:21, 7 January 2024 (UTC)
 * Quibble: US FM is spaced by 200 kHz but not divisible by: stations are on the "odd hundreths". See FM_broadcast_band. DMacks (talk) 11:18, 8 January 2024 (UTC)
 * My bad. Sagittarian Milky Way (talk) 20:11, 8 January 2024 (UTC)
 * Wavelength used to mean something before it got smaller than the radio. People could put up an antenna in the garden for short wave.NadVolum (talk) 23:30, 7 January 2024 (UTC)


 * From the point of view of a physicist or engineer, people use whatever is most convenient. Are you working with diffraction or antennas? Then wavelength. Electronics for transmitters or receivers? Frequency. A boat on water? Wavelength, as the wavelength relative to the length of your boat is what matters most. Unless you're worried that the waves may hit a resonant frequency of your boat. Without electronics fast enough to handle the frequency of visible light, it's always expressed in wavelength. Or, when quantum effects get interesting, photon energy (usually in electronvolts, which directly translates to the voltage on your electronics). When a wave changes speed as it enters a different medium (as happens for sound al the time; the sound speed depends on temperature), the wavelength changes, not the frequency. Sound is usually described by frequency. If wavelength makes more sense than frequency, but it ends up in the denominator of your equation (making the maths harder), you switch to wavenumber. For me, listening to a radio, the fact that the electronics handle a 100 MHz carrier wave is less interesting than the fact that 3 m waves form some diffraction pattern in the room, giving better reception at some points than at others. Maybe most listeners have forgotten that this is related to wavelength?
 * BTW, don't use waves per millimetre. In waves per centimetre, the number is 10 times higher, avoiding fractional numbers somewhat, and it's good to stick to the base unit of your system, which, in cgs, is centimetres. PiusImpavidus (talk) 10:52, 8 January 2024 (UTC)
 * Wavelength is what is referred to when making chips. It determines the feature sizes that can be made whereas frequency doesn't relate to anything much. NadVolum (talk) 11:32, 8 January 2024 (UTC)
 * Yup, and even there, the units we use has changed over time depend upon convenience, at least in the sense of prefix. The Intel 8008 used the 10 µm process, by the time of the first Pentiums, we were on the 800 nm process, and these days we are in the single digits of nm. --OuroborosCobra (talk) 16:08, 8 January 2024 (UTC)
 * I actually wrote something on this a few months ago, with examples across the EM. Basically, it amounts to convenience.
 * ''...the unit of choice is often one of convenience for the application in question. As has been shown above, through dimensional analysis, many of these choices in units are interchangeable or interconvertible with each other, and say the same thing. Let's take that basic one of energy, which happens to be quite applicable to this conversation regarding wavelength (at least as applied to thing like electromagnetic radiation). The unit we are all often taught first in "Physics 101" is the Joule, often explained to us as a N·m. Both mean the same thing. A Joule also is expressed, in SI base, as a kg·m·s-2, but in your classic "Physics 101" thought experiment of pushing a ball or something, that's not a very unit expression. Now, what if we are looking at mid-infrared light, such as that absorbed during molecular vibrations (FTIR spectroscopy, or the energy difference of scatter in Raman spectroscopy)? Let's take the bending vibration mode of a single molecule of water. If we express that in Joules, we get 3.28×10-20 J, which isn't easy to comprehend, to but on an x-axis, or to distinguish between different vibrational energies. We could express it in nm, and we would get 6061 nm, which isn't so bad, until you consider the entire range these vibrations usually take place (and the fact that it can be handy to use a different set of units for vibrations than you do for visible light, just so people immediately know what you are talking about on a plot). Now we get anything from 200000 nm to 2500 nm, which is a somewhat annoying range to work with, and when you're primarily caring about higher or lower energies, having to do the mental gymnastics of "the smaller wavelength is the higher energy" is just an annoying and unnecessary step for this application. So, in the field of vibrational spectroscopy, we use the "wavenumber" unit, which is cm-1. 1 cm-1 = 1/(nm·(cm/107nm)), which might seem annoying math at first, but if you just work in wavenumbers to begin with, that single molecule water bending vibration becomes 1650 cm-1, and the range you are likely to work with in any molecule is 50 cm-1 to 4000 cm-1, which is a lot easier to work with mentally or plot on a graph. The units of choice are about the application often more than anything. In x-ray spectroscopy, nm and cm-1 and J would all be terrible units, but keV (kilo-electron volts) works pretty well, since the range there is usually no more than 0.1 - 2000 keV (usually a smaller range, based on the type of x-ray spectroscopy being conducted, whether you are studying ejection of core electrons or just exciting them between orbital energy levels, etc.)''
 * So yeah, there are times, like visual light, where angstroms might be useful, but they would be terrible for infrared or x-rays. --OuroborosCobra (talk) 15:30, 8 January 2024 (UTC)
 * That makes sense, I didn't realize wavenumber was a sub-4000 thing. If visible light used it the counts would be 14,286 to 25,000 and the hydrogen series below the visible one would be 82,259 to 109,679. Sagittarian Milky Way (talk) 19:52, 8 January 2024 (UTC)
 * Electron-volts I understood, good for X-ray machines and gamma rays and LEDs and some other things. Wavenumbers I didn't understand till your explanation. Sagittarian Milky Way (talk) 20:10, 8 January 2024 (UTC)
 * Somebody collected about an hour of BBC announcements about the UK switchover in 1978: . --Amble (talk) 18:55, 8 January 2024 (UTC)