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Anon questions physics (sh.itjust.works)
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[-] Rooskie91@discuss.online 15 points 12 hours ago

This is your friendly reminder that the majority of people on the Internet are children.

[-] TriflingToad@lemmy.world 5 points 11 hours ago

I don't believe that, I just think the children are more vocal.

[-] Phoenicianpirate@lemm.ee 25 points 18 hours ago

Some asshole needs to remind him of something called evaporation and vapor pressure...

[-] celsiustimeline@lemmy.dbzer0.com 45 points 21 hours ago

Ahh yes, the phenomenon of "somebody cleaned up your dickhead mess you made".

[-] Snowclone@lemmy.world 2 points 12 hours ago

Sounds like the magic table that cleans your plates.

[-] Ashelyn@lemmy.blahaj.zone 8 points 19 hours ago

In dry climates, the water actually will dry itself relatively quickly as long as there's not an overwhelming amount. In more humid areas though, yup.

[-] sugar_in_your_tea@sh.itjust.works 4 points 16 hours ago* (last edited 16 hours ago)

Yup, I live in a desert climate and only clean up big puddles. Anything that doesn't make a splash when I step on it will be gone in under an hour, probably closer to 15 min.

[-] Asafum@feddit.nl 7 points 19 hours ago

Well, water does evaporate at less than 212° at the surface. It's just that the entirety of a pot of water will boil if it reaches 212.

Just think about puddles or whatever after rain on a metallic surface or concrete. It's not entirely being absorbed or cleaned up by anyone.

[-] Aceticon@lemmy.world 55 points 1 day ago

Hence why there's "boiling" and there's "evaporating" - two things that aren't the same hence two different words.

[-] echodot@feddit.uk 31 points 23 hours ago

What exactly is this idiot suggesting some sort of conspiracy to hide all the water?

Obviously the water fairies take it.

[-] ChickenLadyLovesLife@lemmy.world 3 points 12 hours ago

Bigfoot gotta drink something.

[-] julysfire@lemmy.world 3 points 17 hours ago

Big Science doesn't want you to know this one simple trick.

[-] sxan@midwest.social 142 points 1 day ago

The water thought you were so stupid, it left.

[-] OwlPaste@lemmy.world 12 points 1 day ago

Only scientifically correct answer :D

[-] eran_morad@lemmy.world 20 points 1 day ago

Homie should have paid attention in physical chemistry.

[-] absGeekNZ@lemmy.nz 3 points 15 hours ago

That is one bold assumption right there.

[-] SorteKanin@feddit.dk 45 points 1 day ago

My chemistry teacher once explained it to me like below. Does anyone know how much truth there is to this explanation?

Temperature as measured by a thermometer or your finger is an average. Not every single molecule has the same temperature. The molecules constantly bounce around, smashing into each other, transferring heat to each other. By chance, some molecules will get hit in just the right way by other molecules to reach a very high temperature and then it evaporates. So there is constantly a gradient of temperatures among the molecules and the ones with the highest temperature are the ones evaporating, until there is no liquid left at all.

As the average temperature increases, the chance of some molecules reaching a high enough temperature also increases, so warm water evaporates faster than cold water.

This also explains why evaporation cools down (like when you sweat): the molecules with the highest temperature are the ones evaporating, so the average temperature decreases as those high-temperature molecules leave the system. Only the relatively colder molecules are left behind - thus it cools as a whole.

[-] chamomile@furry.engineer 4 points 18 hours ago* (last edited 18 hours ago)

@SorteKanin

This also explains why evaporation cools down (like when you sweat): the molecules with the highest temperature are the ones evaporating, so the average temperature decreases as those high-temperature molecules leave the system. Only the relatively colder molecules are left behind - thus it cools as a whole.

The main principle at work here is the enthalpy of vaporization. When matter changes state, there is an associated amount of energy that is absorbed or released - in the case of vaporization, energy must be absorbed. So when sweat forms on your skin and evaporates, it absorbs heat energy from your body in order to undergo that state change.

For water, the energy involved here is remarkably high, much higher than the energy stored by a few degrees difference in temperature. For example, if you wanted to boil off 1kg of water, it would take about 300 kJ to bring the temperature up to boiling from room temperature and over 2000 kJ to boil it all into steam.

[-] dwindling7373@feddit.it 39 points 1 day ago* (last edited 1 day ago)

I think it's much easier and truthful to stop talking about temperature and introduce speed in that context.

The average speed is what we percieve as temperature, but single molecules can be fast, so fast as to break the boundaries of the liquid pool and shoot up toward space.

Single unbounded molecules are what gas is.

[-] Snowclone@lemmy.world 1 points 12 hours ago

Next explain what mass is in 10,000 words or less. I know two whole ass physics classes aren't enough, so. I'm trying to be generous.

[-] dwindling7373@feddit.it 1 points 5 hours ago

The reason you need to apply force to an object to change its speed.

[-] SorteKanin@feddit.dk 6 points 1 day ago* (last edited 1 day ago)

But temperature is not just the speed of a molecule right? Isn't it also like the "energy" stored in the molecule, or its "wiggling" or something? Like a molecule moving very fast through space can still be at a very low temperature, right?

[-] thebestaquaman@lemmy.world 11 points 23 hours ago

What you're thinking about is the relation between energy, temperature, and heat capacity. When you add energy to a system (e.g. heat) the amount of energy you need to heat it up a certain amount is described by its heat capacity. If your molecules can "wiggle" (i.e. they're multi-atomic) a portion of the energy you're adding will go to increasing the "wiggling" rather than the mean speed of the molecules.

What we perceive as temperature is related to the mean speed of the molecules, so because molecules that can "wiggle" more will require more heat to see the same increase in mean speed as non-wiggling molecules (because some of the heat is going to increasing the wiggling) they have higher heat capacity.

It should also be mentioned that even the concept of temperature is really a statistical concept, so it doesn't really make much sense to talk about the temperature of a single isolated molecule, or even a pair of them. Temperature as a concept starts to be fruitful to talk about in the thermodynamic limit which classically means "a whole shitload of molecules", but (relatively) recent research suggests "a whole shitload" can be as little as 10-30 molecules. Once you go below the thermodynamic limit, we're not really talking about the temperature of a system, but it's energy, which is still well defined (although definitions may vary depending on context). Depending on who you ask, it can make sense to define a temperature also for single-particle systems, but at that point we're talking about applying thermodynamic definitions that work (and are correct in the macroscopic limit) and no longer about what we classically perceive as temperature.

[-] SorteKanin@feddit.dk 3 points 23 hours ago

Thanks, that's useful!

[-] Asetru@feddit.org 6 points 1 day ago

But temperature is not just the speed of a molecule right?

It pretty much is.

Like a molecule moving very fast through space can still be at a very low temperature, right?

That very much depends on the relative speed of the molecule and you. If you're not moving in relation to the molecule, a collision between you and it won't do much. Now try being hit by it (or a bunch of them) at high or even relativistic speeds. The area of you that's hit will surely become pretty hot then.

Like, have you seen footage of asteroid impacts? Have you seen shooting stars? Those are hot. Like, non-figuratively.

[-] dwindling7373@feddit.it 7 points 1 day ago* (last edited 5 hours ago)

Wait it's all models? Always has been.

It's kinetic energy, temperature itself is not a real thing, you are dealing with the bonds that keep water molecules together, if you wiggle hard enought, with enough energy (so... fast enough?) you break free.

I guess another way to look at it is the cloud of elecrons getting more and more messy, so that it destabilizes the bonds...

There's a bit more to it, but it's because of this effect.

There is actually a balance between liquid and gas state, just overwhelmingly in favor of liquid when at normal temperatures. There is a ratio of molecules that will hit each other and transition to gas, and an equal amount gas hitting liquid and condensing. At least when there is a balance between the two sides, aka 100% moisture in the air. Which is not how it is most places.

Normally there is always evaporated water in the air, and anything that evaporated will be moved away in any mildy ventilated area, as you say, it leaves the system. So it never reaches a balance, which is why things dry up at lower temps as water will always evaporate and leave the system.

[-] Tangentism@sh.itjust.works 42 points 1 day ago

Anon doesn't realise that his mum cleared it up. Bet they think there's fridge fairies as well!

[-] Couldbealeotard@lemmy.world 12 points 1 day ago

I used to have this magic basket. I would put dirty clothes in, and later those clothes would turn up clean

[-] sugar_in_your_tea@sh.itjust.works 1 points 16 hours ago* (last edited 16 hours ago)

And folded, right on the bed.

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[-] finitebanjo@lemmy.world 65 points 1 day ago

Each individual molecule did reach an excited state and entered the air, as the air molecules themselves are already highly excited. Also, if the air already has enough moisture then the moisture molecules in the air can accumulate on surfaces that are cold enough that they lose their excited state energy, and a puddle could remain even in warm temperatures because as water leaves the puddle more can also accumulate there.

[-] RegalPotoo@lemmy.world 55 points 1 day ago

Also diffusion and vapor pressure and latent heat - reality is messy

[-] thefartographer@lemm.ee 21 points 1 day ago

Someone needs to clean up this fucking sim, the rules make no sense

[-] taiyang@lemmy.world 22 points 1 day ago

Spaghetti code, unfortunately. Apt, given we boil salted water to cook spaghetti.

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[-] Mango@lemmy.world 10 points 1 day ago
[-] echodot@feddit.uk 4 points 23 hours ago

That's not surprising. That's just how electromagnetism works

[-] Klear@lemmy.world 4 points 18 hours ago

Fucking magnets.

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[-] Gullible@sh.itjust.works 48 points 1 day ago

>go into grocery store
>find both sexy and repulsive people

What the hell, since when have people been ahomogenous?

[-] Dasus@lemmy.world 18 points 1 day ago

ahomogenous

You mean heterogeneous, lol.

[-] Gullible@sh.itjust.works 8 points 1 day ago

Apologies, I meant to write “contrahomogenous”

[-] Zagorath@aussie.zone 22 points 1 day ago

Hey, who are you calling gay‽

[-] thefartographer@lemm.ee 12 points 1 day ago

Some genius

[-] psud@aussie.zone 13 points 1 day ago

The reason being that at any temperature where a liquid can be a gas (over zero degrees Celsius at standard pressure) some of that liquid will become gas.

Over time all of the liquid will become gas

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this post was submitted on 17 Oct 2024
435 points (95.4% liked)

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