/sci/ - Science & Math

>>11640071
Two assumptions typically made in classical optics are
>small angle approximation
>all surfaces are either flat or sections of a circle/sphere
So lenses than focus like they are parabol
>>11639520
>high school
hyper physics
>>11638002
kek
>>11637819
It's both. The more of an insulator a substance is, the more likely it is to donate ions as the charge carrier instead of electrons. A metallic surface isn't going to have ions to donate in any case, because of how metal atoms bond to another. Ceramics possibly do have those ions, though, and if those ions have opposite polarity of the ceramic surface it abrades against, you may get transfer.
>Or more importantly, how could I calculate by myself the energy required to remove an electron from an atom inside a molecule, and the energy required to break a molecule into its ions?
You build a work function.
>Pan, S., Zhang, Z. Fundamental theories and basic principles of triboelectric effect: A review. Friction 7, 2–17 (2019). [woops cant put the link here, google is your friend]
>sections 2.2 and 2.3
Basically its just the difference between the electrostatic potential and the Fermi level.

Little bird weighs four pounds, costs 20.5 cents per pound. Big bird weighs 16 pounds and costs 18.5 cents per pound.

>>11386981
>is no such thing a stupid question
Then what the fuck is this thread
>>>/sci/sqt/

>>11351706
The circuit on the bottom is definitely short-er than the one on the top, but a short circuit it is not. Did I answer your question?
>>11351716
>>11349953
>this system requires no electricity
If you are evaporating water into air in a tower, by the time the air reaches the spout, it will be quite cold. To condense the water and reclaim pure H2O, you need to decrease its entropy. To do this, you need to draw heat out of it. To cool something that is already quite cool, you need something colder. This means refrigeration, which definitely needs a lot of power.
Unless you mean that the "super high speed" air is coming from the top of the spout, in which case your idea makes less sense.
The science of the hotness and wetness of air and how it draws in moisture is called "psychrometrics," by the way. Research that to learn more. If you want more help, you will have to formulate a more specific question.

>>11331036
No matter the motion of a rigid body, you will be able to decompose its motion into the superposition (sum) of some purely rotational about the center of mass, and something purely translational. It's not easy in general. That's why you learn about instantaneous centers.
>should i divide a(about cm) projected in the tangent versor to the point of reference by the r(about cm)?
I think that works. You just have to be very careful about what frame your vectors are in. Remember that [math]\mathbf{a}=\alpha\times\mathbf{r}+\omega\times\omega\times\mathbf{r} [/math]
simple lol
>>11331022
Its complicated
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4241473/#s0005title
>>11331032
>I'm looking for passive
Not gonna make it

>>11173994
>>11173571
Heat is the transfer of thermal energy due to temperature gradients (the phrase "heat transfer" is actually redundant). Work is also a kind of transfer of energy, but neither heat or work is energy per se.

Temperature is related to the average kinetic energy of all the molecules in the sample of a substance and the degrees of freedom that each molecule has. A single molecule cannot have a temperature. The existence of a state function called temperature is implied by the zeroth law of thermodynamics. Historically, thermometers operated on the principle that materials expand and contract depending on their "temperature." The thermodynamic temperature that you and I know today, like the Rankine (based) or Kelvin scales are actually based around the efficiency of a theoretical device called a Carnot engine. You should note that it is completely arbitrary that temperature is a linear scale.
>>11173991
This isn't necessarily true.

>>11159517
people like you make me embarrassed to be STEM. The humanities have a value all their own

>>11119520
How does what work? What's your question?
If an electrical circuit is like a pipe network, capacitors are like reservoirs that fill with water (charge).

>>11022813
We have a simple DC circuit and also a pipe network.
Voltage => height of the pipe over the ground or a pre-defined datum (feet of head)
Current => flowrate of water (gallons per minute or cubic feet per second)
Coulombs => a quantity of water (cubic feet, gallons, acre-feet, whatever). Sometimes water backs up into a reservoir, so it makes less sense to talk about the flow of water (quantity per second) and just talk about quantity. This is what capacitors and dams accomplish.
Joules => joules. A joule or a BTU or a lbs-ft or a psi-cu.ft are all units of energy. Energy is very closely related to voltage/hydraulic head, but has a different unit. Energy is an amount of work that you can accomplish.
kWatt => Power. This is energy delivered per time. If you stick a water wheel in a rushing river, the shaft of the wheel will transmit a certain number of joules per second. If lifting a box is work, lifting a box within a given time is work per time, or power.
>>11022786
Voltage is just an intensive version of potential energy.

>>10959595
The inch-pound-second-faranheit system is completely and utterly based. Good thread.

>>10852704
It's almost like not all branches of academia are science, nor do they need to be.

>>10842505
>t. pretending to not be an undergrad when he clearly is
Σn is a divergent sum no matter how you look at it. It does not equal anything. The -1/12 result comes from analytic continuation, which is something entirely different from the sum "equalling" -1/12.

>>10817051
Because gravity is weak

>>10740958
>Are ciggarettes radioactive
No
Cancerous, yes. Radioactive, no. What kinda smokes you go for, /sci/?
Me? American Spirit Turquoise

>>10696696
How does the mind being purely the result of physical/chemical/biological processes detract from the human spirit? I unironically fucking love science, btw.

>>10689393
Always? The temperatures are constant no matter what? Easy
>construct an alpha type Stirling engine
>constant temperature gradient means no fuel source ever necessary
>free energy forever
>???
>profit

>>10651029
Sexy arms

Electricity is absplutely physical, but not really material. "Current" is concerned with flow of positive charge carriers. It turns out that not only do the real life charge carriers have a negative charge, but that they don't actually move a whole lot. Electricity in a wire is the better thought of as a maintained or alternating electric field. So, it's physical but not really material.

>>10536499
Interesting, I tend to think in grams per centimeter*poise
https://en.m.wikipedia.org/wiki/Poise_(unit)

Grats anon <3
>pure mathematics
Okay but why? What is your bachelors in? Why not get an interesting degree? Which college will you be joining?

>>10478898
Compress a working fluid and pipe it into to your house. Let it it evaporate and flow back out of your house through a throttling device. Once outside, let the fluid condense and compress it once more. Repeat the cycle and the entropy inside your home will decrease.

you cannot be tiger sadly 3:
>>10415794
But this will help

>>10398606
9.81 millinewtons

>using physics to solve a problem that is explicitly unphysical