Successful_Try543
@Successful_Try543@feddit.org
- Comment on Why can't a liquid move faster than the speed of sound in that medium? 17 hours ago:
but it bounces off particles which makes it take a longer path
If I get the explanation on Wikipedia right, it’s not the photon taking a longer path, but the photon is absorbed by electons and re-emitted after a short delay. This effect is what decreases the speed of light in a transparent medium.
In exotic materials like Bose–Einstein condensates near absolute zero, the effective speed of light may be only a few metres per second. However, this represents absorption and re-radiation delay between atoms, as do all slower-than-c speeds in material substances. As an extreme example of light “slowing” in matter, two independent teams of physicists claimed to bring light to a “complete standstill” by passing it through a Bose–Einstein condensate of the element rubidium. The popular description of light being “stopped” in these experiments refers only to light being stored in the excited states of atoms, then re-emitted at an arbitrarily later time, as stimulated by a second laser pulse. During the time it had “stopped”, it had ceased to be light. This type of behaviour is generally microscopically true of all transparent media which “slow” the speed of light.
- Comment on Why can't a liquid move faster than the speed of sound in that medium? 23 hours ago:
Nothing is truly incompressible.
Exactly. One usually speaks of quasi-incompressibility when the resistance against compression (bulk modulus) is much greater than the resistance against shear (shear modulus), which is oft the case for liquids such as water.
However, water has a lower resistance against compression (2 GPa) than e.g. steel (160 GPa), which is considered a compressive material. - Comment on Why can't a liquid move faster than the speed of sound in that medium? 1 day ago:
“Liquid/fluid” and “gas” don’t necessarily mean the same thing scientifically as they do colloquially, they’re actually very close to the same thing.
Both, liquids and gases, are fluids. The main difference is that liquid phases have a free surface, e.g. the level of water in a glas, whereas gases don’t. Their surface is equal to the surface of their compartment.
- Comment on Can you have an infinitely long wavelength of light? Or is there some maximum? 5 days ago:
Otherwise, the answer would be trivial, about 800 nm.
- Comment on xkcd #3115: Unsolved Physics Problems 1 week ago:
Well, if you are willing to coat your head with copper and some tin on top, you can grow yourself some tin whiskers. Yet, I don’t know if they make a good replacement for hair.
- Comment on xkcd #3115: Unsolved Physics Problems 1 week ago:
Deep in the coating, where the Cu6Sn5 [Remark: intermetallic phase of Sn coating and Cu substrate] is present, the deviatoric strain was high. This indicates that the growth of the intermetallic phase causes plastic deformation of the tin coating.
[…]
A short (4 micrometre) radial gradient in hydrostatic stress was observed around the root of the whisker. This gradient together with long-range diffusion from specific regions could provide the driving force for whisker growth.https://portal.research.lu.se/en/publications/tin-whiskers-experiments-and-modelling
- Comment on xkcd #3115: Unsolved Physics Problems 1 week ago:
A colleague of me did his PhD exactly on the last topic.
- Comment on YSK Doctors of Osteopathy in the US seldom practice Osteopathy 1 week ago:
Yet, why do they keep the term ‘osteopathy’ when the don’t do osteopathy, but real, honest osteopathic medicine which would usually be denominated as orthopaedic.
- Comment on If you had a huge slingshot, how much rubber band would you need to send a spaceship into space? 1 week ago:
Actually, the (vertical) velocity of the deflected center point of the rubber band is faster than the axial contraction of the rubber band itself (at that point) which is limited by the speed of sound of the material.
Derivation: Pythagoras, chain rule
- Comment on Tesseract is shutting down 1 week ago:
Same for Eternity.
- Comment on 1 week ago:
Probably the verification by the associated link.
https://stefanbohacek.com/blog/verification-in-the-fediverse/
- Comment on Why does everyone hate Income tax ? 2 weeks ago:
Being paid as some kind of tax isn’t income tax only, it’s also e.g. VAT.
- Comment on Are display sizes always measured in inches? 2 weeks ago:
Additionally, at least in German, the term inch is usually translated into the local counterpart Zoll.
- Comment on What are the differences between 1) probabillities, 2) possibillities, and 3) plausabillities? 3 weeks ago:
Thank you.
- Comment on What are the differences between 1) probabillities, 2) possibillities, and 3) plausabillities? 3 weeks ago:
If you throw a coin, the result has two possibilities: It may show either the obverse side (head) or the reverse (tails). These possibilities have equal probability (“50:50”).
- Comment on What if you used a flamethrower as a snowblower? 1 month ago:
From the energy perspective, you need a certain amount to increase the temperature of the snow form initial temperature to over 0°C, and another amount to overcome the latent heat (heat of transformation) from solid ice to liquid water.
The latter, the heat of transformation, has been used for making ice cream whitout a refrigerator: Melting ice cubes in a large bowl with the help of salt was used as a cooling agent to freeze the container of smaller bowl placed inside the larger one. - Comment on Any FOSS alternatives to macrodroid/Tasker? 1 month ago:
The actions, e.g. “Keep screen on” are to be specified in a “Profile” of your choice, e.g. create a new, empty one.
To apply this “Profile” based on the app and battery level, you have two options:
Either create an empty “Event” where you specify both, battery level and foreground app (application sensor).
Or: Create an Event for the app with medium priority and assign a high priority to the standard “battery low” event, e.g. 10.
- Comment on Any FOSS alternatives to macrodroid/Tasker? 1 month ago:
Eventually PhoneProfilesPlus.
- Comment on This meme goes way back 1 month ago:
Big Tiddy Gorgon Girlfriend :-p
- Comment on How to check whether a particular url is safe or not ? 1 month ago:
Tbf, the article is from 2018. It possibly has changed in the meantime.
- Comment on This meme goes way back 1 month ago:
Yet, the Medusa wasn’t involved in that story.
- Comment on How to check whether a particular url is safe or not ? 1 month ago:
Recently it has become a problem that optical twins of legit URLs exist, where some letters have been replaced by alike letters from different alphabets, see e.g. the list in this link.
- Comment on YSK how to unclog a toilet 1 month ago:
Doesn’t “hot water” refer to what you can get out of the faucet, so like 60 °C (140 °F), not boiling water?
- Comment on YSK how to unclog a toilet 1 month ago:
How many courics?
- Comment on [deleted] 1 month ago:
I guess a bread knife works pretty well for slicing roast, i.e. the dish, not raw meat.
- Comment on [deleted] 2 months ago:
Indeed.
- Comment on [deleted] 2 months ago:
practice pushing the gas pedal just enough to hold the engine at 3000 RPM or so. Not making crazy racing noises, just a nice steady “the engine is running normal-fast-ish”
Depending on the type of car, this might usually be somewhere between 1500 and 2000 RPM, 3000 RPM are more typical for a sports car.
- Comment on xkcd #3084: Unstoppable Force and Immovable Object 2 months ago:
There is no force without interaction, just linear momentum.
- Comment on [deleted] 2 months ago:
As I’ve understood, it offers the ability to download files from different ‘one-click’ hosting platforms at ‘premium’ speed without having to pay for ‘premium’ at each platform individually.
- Comment on [deleted] 2 months ago:
Feel free to indicate the imaginary unit with ‘X’ or some other distinct symbol during your derivations.