/sqt/ /qtddtot/ - stupid questions thread

[Anonymous No.14689399]

Previous thread: >>14661473

>what is /sqt/ for?
Questions regarding math and science. Also homework.
>where do I go for advice?
>>>/sci/scg or >>>/adv/
>where do I go for other questions and requests?
>>>/wsr/ >>>/g/sqt >>>/diy/sqt etc.
>how do I post math symbols (Latex)?
rentry.org/sci-latex-v1
>a plain google search didn't return anything, is there anything else I should try before asking the question here?
scholar.google.com
>where can I look up if the question has already been asked here?
>>/sci
https://eientei.xyz/
>how do I optimize an image losslessly?
trimage.org
pnggauntlet.com

>where can I get:
>books?
libgen.rs
z-lib.org
stitz-zeager.com
openstax.org
>articles?
sci-hub.st
>book recs?
sites.google.com/site/scienceandmathguide
4chan-science.fandom.com/wiki//sci/_Wiki
math.ucr.edu/home/baez/physics/Administrivia/booklist.html
>charts?
imgur.com/a/pHfMGwE
imgur.com/a/ZZDVNk1
>tables, properties and material selection?
www.engineeringtoolbox.com
www.matweb.com

Tips for asking questions here:
>attach an image (animal images are ideal. Grab them from >>>/an/)
>avoid replying to yourself
>ask anonymously
>recheck the Latex before posting
>ignore shitpost replies
>avoid getting into arguments
>do not tell us where is it you came from
>do not mention how [other place] didn't answer your question so you're reposting it here
>if you need to ask for clarification fifteen times in a row, try to make the sequence easy to read through
>I'm not reading your handwriting
>I'm not flipping that sideways picture
>I'm not google translating your spanish
>don't ask to ask
>don't ask for a hint if you want a solution
>xyproblem.info

[Anonymous No.14689437]

Why is neuroscience based?

[Anonymous No.14689562]

>>14689399
Lmao.

Unanswered questions:
Maths questions:
>>14664565
>>14675394
>>14687807

Physics questions:
>>14662267
>>14674791
>>14678093
>>14685221
>>14687047

Chemistry questions:
>>14671130

Stupid questions:
>>14662160
>>14665160
>>14665585
>>14665675
>>14667362
>>14667731
>>14667797
>>14668078
>>14668790
>>14671121
>>14671676
>>14673803
>>14675190
>>14676208
>>14677365
>>14677535
>>14678083
>>14683123
>>14685434

[Anonymous No.14689837]

Ok bros super duper curious, what is the deal with all these olympiads? Like I know of the math Olympiad and that’s like math questions but they have them for all sorts of subjects like linguistics, and from what I’ve seen of linguistics they just seems to make up random shit and then ask you questions about it as if they’re real languages which seems completely and insanely stupid.
Also what’s with all these people denying that people who do well at the math Olympiad go on to do better in math than other people? Is it just sour grapes or do they have a point?

[Anonymous No.14689997]

what field of study should i focus on if i want to become a girl with a huge cock

[Anonymous No.14690026]

Will it damage a capacitor rated at 50v if you charge it with high impedance pulsed 200VDC, but only until it's charged to 50v?

[Anonymous No.14690053]

>>14689837
Social people like to join groups. Hypersocial people also like to push or pull other people into groups. (Some are even uncomfortable around people who haven't joined a group.) Olympiads are mostly a way for hyperjoiners to push people who like to do nonjoiner things into a group.

[Anonymous No.14690443]

are online coding bootcamps an actual path towards a job

[Anonymous No.14690788]

I'm solving a constrained optimization problem with scipy's SLSQP algorithm on Python but the solution violates some constraints even if I provide the true solution as a starting point (the solver returns a "better" solution but some constraints don't hold). What's going on? How can I make SLSQP not ignore my constraints? Are there maybe better constrained optimization solvers on Python?

[Anonymous No.14691009]

Can someone tell me what r1, r2, and r3 stand for? I think they're the columns of R. I also don't understand how to calculate the partial derivative in (7).

u is a 3x1 column vector
R is a 3x3 rotation matrix

[Anonymous No.14691014]

>>14689837
>Also what’s with all these people denying that people who do well at the math Olympiad go on to do better in math than other people? Is it just sour grapes or do they have a point?
I doubt anyone's denying that these olympiad kids are going to do better, that's already true by virtue of their extracurricular interest in math, the argument to be had is that competitive math does not exclusively test your mathematical ability, (e.g experience and rote memorisation of tricks).
I think it's that people have been accustomed to all these 11 year old asian gold medalists not accomplishing much in the way of research when they grow, but there are definitely ego driven sour grapes people

[Anonymous No.14691081]

What are some zeroes of the Riemann Zeta function with real part equals 3?

[Anonymous No.14691147]

Ate trans women women?

[Anonymous No.14691153]

>>14691147
that depends on the definitions used.

[Anonymous No.14691159]

>>14691009
>what is this nonsense that I found somewhere and posted with no context and nothing at all?

r1,r2,r3 stand for subindexes anon.

[Anonymous No.14691160]

>>14691081
3+-ξi for example

[Anonymous No.14691335]

>>14690788
Try COBYLA. Maybe slsqp will do better with derivatives of the constraints.

[Anonymous No.14691406]

What will happen if we get a really bad geomagnetic storm like the Carrington Event again? Will our infrastructure be destroyed or will we be able to recover quickly? What's the plan?

[Anonymous No.14691468]

>>14689562
>>14685221
>>14683295
Tensors related thread, still no answer

[Anonymous No.14691493]

>>14691468
Depends on the type of the tensor

[Anonymous No.14691515]

>>14691493
Right

[Anonymous No.14691722]

does pregnacy increase breast size permantly?

[Anonymous No.14691846]

>>14689399
The more I read about finasteride the worse it seems for you (don't worry this post is about biochemistry/endocrinology).
Finasteride is a steroidal 5AR inhibitor which prevents hair loss by nuking DHT but it also deprives you of neurosteroids like allopregnanolone which are involved in preventing depression and even seizures. I feel like there's no way it's safe to be depriving yourself of those no matter how many sources (I am most checking the national institute of health) tell me it's well-tolerated and significant side effects are rare.
Nonsteroidal options like saw palmetto and other herbal remedies, applied topically, I am less concerned about because they're way less effective and topical application reduces systemic dose but I feel like inhibiting 5AR by enough to matter is just asking for trouble.
I guess what I am asking is, can someone with a better grasp on endocrinology give me a QRD on the risks of 5AR inhibitors and why the might/might not be as bad as I think?

[Anonymous No.14691910]

>>14691722
No. I heard they can even deflate after breastfeeding.

[Anonymous No.14691921]

Where is the last implication coming from? It would require g to be injective, but nothing as such is given.

[Anonymous No.14691945]

>>14691910
Unfortunately

[Anonymous No.14691988]

>>14691910
dam im not getting a vasectomy now. I like those big breast.

[Anonymous No.14692233]

[math] \forall x \,\forall y \; P(x,y) \iff Q(x,y)[/math]
also means that:
[math] \forall x \,\forall y \; \neg P(x,y) \iff \neg Q(x,y)[/math]
Is this correct?

[Anonymous No.14692239]

>>14692233
yes

[Anonymous No.14692242]

>>14692239
lovely!

[Anonymous No.14692282]

>>14689399
what's the difference between an electro-volt and volt?

[Anonymous No.14692297]

>>14692282
An electron volt is a unit of energy, specifically the kinetic energy gained by an electron being accelerated across a potential difference of one volt. For comparison, a joule is a coulomb-volt (a volt is a joule per coulomb, or a watt per ampere). The charge of an electron is 1.602e-19 coulombs, so an electron-volt is 1.602e-19 joules. Electron-volts are normally used for measuring the energy of individual atomic or sub-atomic particles.

[Anonymous No.14692305]

>>14692297
so is 1 V = 1 eV?

They seem like the same thing

[Anonymous No.14692308]

>>14692305
wait nm, it would be 1 electron * 1 V

so 1.602e-19

[Anonymous No.14692336]

>>14691160
What is the value of ξ?

[Anonymous No.14692423]

>>14692233
yes

[Anonymous No.14692434]

I need the radial profile of charge density for a carbon atom. Where/how can I find it? I just need a qualitative plot

[Anonymous No.14692587]

If: [math] \forall \epsilon > 0 \left(y - \epsilon < x < y + \epsilon\right)[/math], where [math] y,x \in \mathbb R[/math], does it necessarily mean that [math] y=x[/math]?

[Anonymous No.14692601]

>>14692587
Nope, but using a limit you will get that

[Anonymous No.14692608]

Obviously the area below 1/x refers to its integral lnx. But what does the "area above" 1/[x] refer to?
Note here [x] refers to the step function such that [x]

[Anonymous No.14692619]

>>14692608
Pic related, internet cut out.

[Anonymous No.14692632]

>>14692587
Wikipedia's proof of IVT uses this fact though in the final step.

[Anonymous No.14692674]

Give me an (made up it you want, take a lemon stand, a restaurant, a car manifacturer) example where I can clearly see how
>earnings
>profit
>revenue
>free cash flow
are different and why

[Anonymous No.14692690]

>>14692308
>1 electron * 1 V
It's 1 electron *charge* times 1V
>1.602e-19
You're missing the unit there. The unit would be CV, which is the same as Joule.

[Anonymous No.14692706]

>>14692674
I start a magic pube dispensary. You buy everything cause you seem like the kind of guy who would. That is our REVENUE, also known as EARNINGS.

Most of that money goes back into our magic pube psy op we are running to convince you that there are real benefits to the magic pube lifestyle. It also helps cover up we did 9/11.

The money left is our pube PROFIT. Our profit plus money we have available to use at any time is our FREE CASH FLOW.


I made an easy acronym for you to Remember
Every
Pube
Raises
Funds

Hope this helped

[Anonymous No.14692717]

>>14691014
Well the argument would more so be that it doesn’t improve your math abilities as much as doing something else in that same time frame, since people spend a lot of time preparing for the competitions and it’s like yeah doing more maths makes you better at math. But what about the other subjects, as I said linguistics seems to be absurd if they’re just making shit up like it’s nonsensical and what really is the point of it outside of just having a competition about something. This is like a history competition where they make up some historical event and then give you primary resources for you to figure out what happened.

[Anonymous No.14692729]

>>14692619
[eqn] \int_1^n \left( \frac{1}{x} - \frac{1}{\lfloor x +1 \rfloor } \right) dx \\
= \sum_{k=1}^{n-1} \int_k^{k+1} \left( \frac{1}{x} - \frac{1}{\lfloor x +1 \rfloor } \right) dx \\
= \sum_{k=1}^{n-1} \int_k^{k+1} \left( \frac{1}{x} - \frac{1}{k+1} \right) dx \\
= \sum_{k=1}^{n-1} \left( \log(k+1) - \log(k) - \frac{1}{k+1} \right) \\
= \log(n) - H_n
[/eqn]

[Anonymous No.14692785]

>>14692729
Sorry for asking since you answered but where does this -1/[x] come from? I don't see how this is the area above 1/[x+1], or what would that even refer to.

[Anonymous No.14692877]

>>14691335
COBYLA makes things worse and providing the Jacobians makes things better but not by much (the constraints are still violated but by a lesser degree). I rewrote my code on MATLAB and its SQP algorithm gives me a good constraint-respecting answer. Maybe I got lucky, or maybe MATLAB's solvers are just more robust. It's a shame I have to turn to proprietary software. If I'm going to keep using MATLAB for my research, that means my code isn't going to be as reproducible for others.

[Anonymous No.14692890]

Stupid question: is there a way to find out if a thread was purged by a janny or deleted by OP?

[Anonymous No.14692969]

>>14692717
>what really is the point of it outside of just having a competition about something
It shows that you know shit about the subject, so you could put it in the resume. Many universities accept Olympiad performance as a valid criteria for admission. Some pure math universities may offer a waiver for entrance exams if the student has performed well in Olympiad. And socialisation with like-minded people.

I don't see how the linguisitics is absurd at all. That's like saying math exams where they just make up problems is absurd.

>This is like a history competition where they make up some historical event and then give you primary resources for you to figure out what happened.
Not comparable since history is the understanding of what already has happened. Linguistics is the study of languages. You can't just make up history but you can certainly make languages. The entire idea behind linguistics is to find common patterns in an unknown language, so that's what they test in Olympiads.

[Anonymous No.14693017]

is there a systematic way to tell if a post/reply was written by a bot?

[Anonymous No.14693069]

>>14692706
fucking A anon, that guy couldn't appreciate it, but I do

[Anonymous No.14693114]

Testing something real quick.
>>>/g/wdg

[Anonymous No.14693394]

>dark room
>bright exterior
>room has window with typical glass
If you're looking from the outside in, you will see a reflection of the exterior. If you're looking from the inside out, you'll see the exterior.

Would it be possible to see the interior from the exterior without changing their respective brightness?
Either by shining a certain kind of (visible or invisible) light into the window, or by using special glasses?
Do some rays get reflected but not others? As in, you can see the interior by isolating the UV or the IR light?

[Anonymous No.14693402]

>>14693394
I'm not sure you understand the basic concept. Glass reflects a certain percentage of light. Let's say 10%. If you're looking from the inside, where there's little light, you get 10% of little and 90% of a lot (the outside you can see).
If you're outside, the light you get is 10% of a lot and 90% of little. Depending on the brightness, the reflected 10% can be a lot more than the light that's from the inside.
>Would it be possible to see the interior from the exterior without changing their respective brightness?
>Either by shining a certain kind of (visible or invisible) light into the window
Um .. how is shining light through the window not changing the respective brightness? Also, you have to shine it in a way that the reflections don't blind you. Invisible light will have no magical effect.
>or by using special glasses?
Now that's an interesting one. Depending on the angle under which light is reflected, it is actually polarized. So if you have a polar filter and stand in the right position, you can block out all reflections and see half of the light that comes from the inside.
>Do some rays get reflected but not others? As in, you can see the interior by isolating the UV or the IR light?
If it's reflective for light, it's likely reflective for IR and UV as well. Thermal cameras suffer from reflections.

Good luck stalking your crush anon.

[Anonymous No.14693454]

Can someone explain what this means and how they got it? I hate it when they do this.

What does the quadratic formula have to do with a? If we did like f(999) then it would be a^(999-2)

[Anonymous No.14693623]

>TUG 2022 online conference
>half the keynotes are about converting to markdown, switching to markdown or using markdown
Why the fuck all this shilling holy fuck. I will never switch from based PDF, fuck off.

[Anonymous No.14693661]

>>14693623
I'm not sure this would be my number one priority right now.

[Anonymous No.14693674]

>>14690443
Bootcamps arent a path to a job, let alone online ones.
Do a software engineering degree, dont bother with CS if you dont want the maths.

[Anonymous No.14693684]

>>14693661
What, you don't write your thesis on the front-lines using pen and paper? You are missing out.

[Anonymous No.14693686]

What are the quantum revolutions?
Is it a meme, or are we actually witnessing the birth of something that will change our lives just like the birth of computer science changed our world forever?

[Anonymous No.14693707]

>>14689399
I'm trying to solve this integral here
[math]\int^{\infty}_0\frac{t}{e^t-1}\text{ d}t[/math]
performing a u sub and then integrating with partial fractions works, but I do not want to use of the definition of the dilogarithm.

(Curiously partial fractions causes an indeterminate form which is nice ig)

In the end, I decided to perform a contour integral with a keyhole contour, the "hole" facing towards the positive real axis, but I've been having some trouble doing this.

I've noticed that [math]\int^{\infty}_0\frac{t^{s-1}}{e^t-1}\text{ d}t=\int^{\infty}_{-\infty}\frac{e^{st}}{e^{e^t}-1}\text{ d}t[/math] but I'm not sure if this is of any help or not.

Help is appreciated on how to contour integrate this :D

[Anonymous No.14693718]

>>14693684
I have a GPD MicroPC for that

[Anonymous No.14693899]

Biology: During the creation of gametes, are the genetic crossover spots completely random or are there some base sequences that don't work anyone when broken up and are therefore someone protected?
If it is random, how does biology deal with this? Does this also mean that all the genes that are the same in humans are also at the same spot? Gene shuffling doesn't happen in animals?

[Anonymous No.14693908]

How was (2.36) derived from (2.35)?

[Anonymous No.14693911]

>>14693908
Meant to post this

[Anonymous No.14693959]

>>14693454
a is the golden ratio, it satisfies the given quadratic equation

[Anonymous No.14693969]

>>14692587
yes obviously.

if y <> x (say y>x without loss of generality) then you can use e = (y-x)/2 >0
then y-e = (y+x) /2 >x, which contradicts the assumptions that for any e >0, y-e<x

[Anonymous No.14693984]

>>14693911
using 2.33 and by summing from m=1 to n-1, you get ln(n) - ln(1) = 1/2 sum_m=1^(n-1) 1/m^2- 1/3 sum_m=1^(n-1) 1/m^3 etc.

when you subtract this from the infinite sums, you're left with the sums for m=n to infinity

[Anonymous No.14694199]

i need someone to explain this to me
>smoke tobacco: very bad
>smoke weed: good
>heat with wood and breathe smoke daily: good
it's all smoke. it's all being inhaled. it's all from plants. the only major differences that i can think of are the active neurological compounds. yet, i hear people talking all the time about how horrible smoking is, or how great smoking weed is for you while it's literally all just burning plants.

my family has heated with wood for 14 years, i've been inhaling wood smoke almost daily for 8 months of all those years in long, cold Maine winters. i have inhaled small amounts of secondhand tobacco smoke. my heart has not failed, my lungs are still fine, i can breathe and run. am i in shape? no, but that's no fault of smoke, that's because i'm a lazy bastard.

but anyway, tldr: why are some smokes so bad and some smokes so okay/not bad?

[Anonymous No.14694413]

>>14693984
Sorry if I'm misreading something but I don't see how that demonstrates how (2.36) was derived from (2.35)

[Anonymous No.14694453]

>>14689399
>that pic
What did he mean by this?

[Anonymous No.14694460]

>>14691406
Not this anon but I reckon this event will occurs in 2025.

[Anonymous No.14694485]

what does it mean if there's lots of blood after wiping but no blood in the shit? aam I gonna die? do I have enough time to write my will?

[Anonymous No.14694570]

>>14694460
That's what I heard too. The last time there was a big solar super storm it missed us by 9 days. The sun moves in cycles so in 2025 we will be in the most danger of getting hit. I'm surprised more people aren't talking about it. Are we prepared for it? If we're not it's going to put 2020 to shame with the amount of damage and lives lost because we can't use electricity (hospitals, gps, internet, etc.)

[Anonymous No.14694583]

Any books about learning to learn? I keep having bad anxiety about wasting my time with learning things wrong which ends up with me not learning at all.

[Anonymous No.14694854]

>>14694199
>smoke tobacco: good as a drug, bad for health
>smoke weed: good as a drug, bad for health but at least it's not as excessively carcinogenic as tobacco
>heat with wood and breathe smoke daily: bad
no idea why you thought that last one was good for some reason??
>my family has heated with wood for 14 years, i've been inhaling wood smoke almost daily for 8 months of all those years in long, cold Maine winters. i have inhaled small amounts of secondhand tobacco smoke. my heart has not failed, my lungs are still fine, i can breathe and run. am i in shape? no, but that's no fault of smoke, that's because i'm a lazy bastard.
do you not have a chimney? what the fuck
is main really a pre-stone age hellscape?

[Anonymous No.14694912]

>>14693969
Then due to density of rationals, every real number is equal to a rational number????

[Anonymous No.14695039]

>>14694912
>disclaimer: real numbers don't exist, but let's suppose they do for a minute
No. find me 1 example of x being irrational and y being rational that also satisfies the given property

[Anonymous No.14695219]

>>14695039
You don’t understand. For all y > epsilon > 0, y - epsilon < y + epsilon, but then there exists a rational number x in between them. Therefore, all real numbers can be expressed as a rational number.

[Anonymous No.14695274]

>>14694413
can't be bothered to type this shit out, sorry for the writing

[Anonymous No.14695377]

>>14693707
isn't this the most famous example for differentiation under the integral sign?
or Leibniz rule (Feynmans trick, for normies)

[Anonymous No.14695444]

>>14695274
Thanks alot, I didn't even notice the summation when from 1 to inf , and then n to inf at the end.

[Anonymous No.14695485]

>>14695444
np fren, glad I could be of help

[Anonymous No.14695503]

>>14693707
>>14695377
It looks more like an application of the geometric series formula to me
[eqn] \sum_{n=1}^\infty e^{-nt} = \frac{e^{-t}}{1 - e^{-t}} = \frac{1}{e^t - 1}[/eqn]
So

[eqn]\int_0^\infty \frac{t}{e^t - 1} dt \\
= \int_0^\infty \sum_{n=1}^\infty t e^{-nt} dt \\
= \sum_{n=1}^\infty \int_0^\infty t e^{-nt} dt \\
= \sum_{n=1}^\infty \frac{1}{n^2} \\
= \frac{\pi^2}{6}
[/eqn]

[Anonymous No.14695530]

>>14695503
Slick, but I wouldn't be surprised if [math]\sum_{ n = 1 }^{ \infty } \dfrac{ 1 }{ n^2 }[/math] was what anon
was originally trying to evaluate.
IIRC in the Feynman evaluation you make the way back in your post and then use the Feynman trick like the other anon mentioned.

[Anonymous No.14695638]

>>14695530
Since you happened to mention the sum in pic related, how the hell did this asshole (author of a Radical approach to analysis) obtain these results?

[Anonymous No.14695652]

How did the NASA's Apollo mission crew managed to avoid Van Allen belt radiaction?

[Anonymous No.14695674]

>>14695638
Use the monotony of the integral sign.
[eqn] \sum_{m=n}^\infty \frac{1}{m^2} = \sum_{m=n}^\infty \int_m^{m+1} \frac{dx}{m^2} > \sum_{m=n}^\infty \int_m^{m+1} \frac{dx}{x^2} = \int_n^\infty \frac{dx}{x^2} = \frac{1}{n}[/eqn]

[eqn] \sum_{m=n}^\infty \frac{1}{m^3} = \frac{1}{n^3} + \sum_{m=n+1}^\infty \int_{m-1}^{m} \frac{dx}{m^3} > \frac{1}{n^3} + \sum_{m=n+1}^\infty \int_{m-1}^{m} \frac{dx}{x^3} = \frac{1}{n^3} + \int_n^\infty \frac{dx}{x^3} = \frac{2+n}{2n^3}[/eqn]

[Anonymous No.14695681]

>>14695674
The ">" in the last line should be a <.
In the interval [m-1 , m) we have that m > x so 1/m^3 < 1/x^3.

[Anonymous No.14695692]

>>14695652
they said they "lost" and "destroyed" the technology to do it

[Anonymous No.14695753]

ESL here: what does all but finitely many [math] n[/math] mean?

[Anonymous No.14695766]

>>14695753
for every neighborhood of p, there can only be a finit number of n's such that p_n are not in that neighborhood.

basically it's ok if p_0 and p_14 are not in the neighborhood of p you're looking at, the sequence can still converge towards p.

[Anonymous No.14695774]

>>14695766
ধন্যবাদ

[Anonymous No.14696280]

>>14694854
>do you not have a chimney? what the fuck
i do, but the second you open the door a lot of smoke will come out. there's nothing you can do about that.

[Anonymous No.14696366]

Can someone explain how the negative sign becomes positive (red) by changing the terms underlined in yellow?

[Anonymous No.14696386]

>>14696366
Was there supposed to be a pic attached to your post or?

[Anonymous No.14696402]

>>14696366
Forgot pic

[Anonymous No.14696403]

>>14696386
yes, mb>>14696402

[Anonymous No.14697019]

>>14693899
I found it out myself. These are indeed certain spots where it's more likely that the chromosomes will cross over

[Anonymous No.14697088]

>>14696402
[math]a-b=-(b-a)[/math]

[Anonymous No.14697092]

>>14695377
Ah hmm. Where would I introduce the variable? Or is it just [math]I(s)=\int^{\infty}_0\frac{t^{2-1}}{e^t-1}[/math]?

>>14695503
>>14695530
Yea, I'm trying to use the integral to evaluate that sum lol. Hence why I also said I wouldn't like to use the dilogarithm since by definition [math]\operatorname{Li}_2(1)=\sum^{\infty}_{n=1}\frac{1}{n^2}[/math] and it kinda ruins the purpose. Anyhow, since Leibniz rule seems the way to go, is my above function correct?

[Anonymous No.14697116]

>>14694453
all avatarfags go to Hell

[Anonymous No.14697194]

>>14693959
so its literally magic, thank you

[Anonymous No.14697255]

>>14697088
Thank you fren

[Anonymous No.14697310]

I got two questions.

1. If Global Warming is caused by too much carbon in the atmosphere, why is no one talking about going up and getting it back, to use it again, somehow I don't know energy I learned that shit in high school like 10 years ago fuck.

2. If Earthquakes are caused by plates building pressure, wanting to move, breaking to move and then stopping at either enough rock or little enough pressure to stop, why don't we just like, plan that ourselves?

We've controlled against floods, why not earthquakes? Could we, like, map out the plates and their points of collision and create a sort of 'massaging machinery' to the earth that makes them move slowly and with control, e, carefully adjusting the pressure to produce a managed planned Cat 3 or 2 earthquake or someday even better? Like just a constant controlled adjustment of the earth so no one detects it? I mean I get we don't got the shit to do that, RIGHT NOW, but is that like a thing that someone could theoretically do, and what would they have to do to do that, like how do you 'massage' out an earthquake, safely? I'm just imaginging these underground pressure blasting machines, mapping out pressure for controlled shaking period that can't build up into the bigger Quakes we've faced before.

Yeah I'm sure there's some new thing we can't fuck up the lava for and that adds a new problem, but one day at a time guys humanity's a journey not a destination, let's stop having quakes for 50 years and deal with the new shit another generation later.

[Anonymous No.14697350]

>>14697310
nigga what the actual fuck
have you ever even read a book?
why are you here?
just to make us suffer?

[Anonymous No.14697398]

>>14671130
Colder is better, you'll get more efficient condensation of your solvent and save some life on your vacuum pumps. How cold are you talking?

[Anonymous No.14697402]

What's the point of teaching yourself STEM stuff if employers won't care if you don't have some kind of formal education in the thing in question and you can't really apply your knowledge in a lot of fields without a well-equipped lab?

[Anonymous No.14697405]

>>14697402
the point is that you enjoy it
if you don't, give up now

[Anonymous No.14697415]

>>14697405
Yeah but there's only so much enjoyment that can be reaped from just sitting on existing knowledge. What if you want to innovate?

[Anonymous No.14697426]

>>14697415
then you innovate
why the fuck would you care about what some hr trog wants if you're going to make your own product?

[Anonymous No.14697434]

>>14689399
Math problem for /sci/
You have two tanks with the same chemical.
Tank A is mixed at 64oz of chemical per 100 gallons and has 1000 gallons.
Tank B is mixed at 12oz chemical per 100 gallon and currently has 60 gallons of solution.

How many gallons from tank A do you need to add to tank B to bring the solution to 34 oz/ 100 gallons? How did you arrive at your answer?

[Anonymous No.14697435]

>>14697350
What's the fucking thing I'm not getting here?

We put too much carbon or chemicals of some shit in the air and that's like causing energy that comes from the sun to stay around too much and that means the global energy that powers the cycles of storms and droughts and heats and colds are so extreme they change the environment and bring dangerous giant storms, like a Global Overclocking gone fucky, so we like, take the shit out the system. Collect the 'energy' or whatever the fuck's causing it and it can be stopped, or it subsides quickly or whatever, just another thing to collect and keep and not JUST fucking tax us, right? I want this actual global warming shit to have a solution that isn't just 'weather the storm/conserve' like a little bitch, I want to FIX the system, I want to roll shit back, how we doing that? Carbon? Chemicals? I don't know.

And that's what earthquakes are, pressure that builds and then would ricochet essentially accross the plates and affect the pressure the plates build, and those quakes, affect the others, and especially in a place like the ring of fire, moving that plate to just release pressure, or utilize pressure to coordinate planned volcanoes to build up islands for land for peoples to live on, to mechanically automate our currents, or even adjust our currents as needed. If we master the shaping of the earth, couldn't we build new continents?

This IS the stupid question thread, don't be mad about the ONE thing.

[Anonymous No.14697441]

>>14697435
if YOU want to fix the problem then YOU should be the one doing some research and answering other people's stupid questions
if YOU just want to be spoonfed, then YOU aren't going to fix shit, you're just going to sit there while other people do it for YOU

[Anonymous No.14697454]

>>14697092
Wait hold on what, I can't get anything to work lol. Introducing parameters into the numerator creates logs which can't be dealt with.

Introducing parameters in e^st or (e^t-1)^s don't seem to be working at all either.

Where do i put the parameter?

[Anonymous No.14697786]

>>14694199
Regular inhalation of wood smoke is considered one of the world's leading causes of preventable death and morbidity, anon. It's definitely not good for you.

[Anonymous No.14698379]

solve this

[Anonymous No.14698380]

>>14698379
using this

[Anonymous No.14698407]

>>14698380
Uh huh, so we just scale the problem down to simpler squares and pray there's a pattern?

Or do as Euler might've done and trial and error till nightfall.

[Anonymous No.14698435]

>>14689399
Can somebody please help me understand pic related? Why is angle g equal when doing the cross product like this?

[Anonymous No.14698437]

>>14698435
Vectors s, r, a have a 90 degree angle btw.

[Anonymous No.14698439]

>>14698437
Ffs, I'm tired anons. I mean s, a have 90 degrees between them ofc.

[Anonymous No.14698441]

>>14698407
suduku is solveable, but from there no idea.
there is somewhat of a pattern, but nothing to draw conclusions with.

[Anonymous No.14698442]

>>14694485
You've wiped too hard for too long and torn the delicate skin of your butthole

[Anonymous No.14698451]

>>14695652
Apollo 11’s trajectory avoiding the worst of the belts.

[Anonymous No.14698455]

Considering medical anatomy and wolf's law/pyshics,etc.can I make my skull and general bones,EVERY bone from EVERY angle,strong enough to resist blunt baseball bat hits/axe and iron shovel impacts/,etc?

[the best male hominid since sentience started No.14698472]

>>14698455
Also a related question:Im going to be the first male hominid to do 3-5K reps per excercise and 5 excercises per muscle;what will happen after a daily full-body such regimen?

[Anonymous No.14698902]

>>14697435
The primary mechanism for removing CO2 from the atmosphere is turning it into biomass (mainly trees). The problem is that we're putting it up there much faster than we can remove it. Fossil fuels (coal, oil, methane) accumulated over millions of years, and we've taken a significant proportion of the total and turned it into CO2 in the space of little over a century (since the start of the industrial revolution, basically).

Ideally, we need to remove at least 500 billion tons of CO2. That would reduce the concentration by around 100 ppm; it's 400+ ppm now, was around 250 ppm before the industrial revolution. 500 billion tons works out to around a thousand tons per km^2 of land.

[Anonymous No.14699072]

Do men have higher iqs than women? or do women have higher iqs than men?

[Anonymous No.14699299]

>>14699072
There's no difference. However men have a higher variance, so more geniuses but also more smoothbrains and retards.

[Anonymous No.14699392]

Can someone please help with picrel

[Anonymous No.14700034]

>>14699072
>Do men or women score better on a measure of intelligence that was balanced to even out the scores between the two
Whatever the answer is only says something about the test itself.

[Anonymous No.14700187]

>>14699392
I never studied complex projective spaces but can't you just explicitly give an homeomorphism?
A point of S^2 x S^2 is just a pair of triples of real numbers ((a,b,c),(d,e,f)) with a^2 + b^2 + c^2 = 1 and d^2 + e^2 + f^2 = 1. So maybe try
[eqn]
z_0 = a + i \cdot d \\
z_1 = b + i \cdot e \\
z_2 = c + i \cdot f \\
z_3 = \sqrt{-z_0^2 - z_1^2 - z_2^2}
[/eqn]

[Anonymous No.14700229]

Is it possible for some animal to have a disorder where their visual perception is delayed by a significant amount of time? Maybe they could hear in real time, but visually it would be delayed. They'd never be able to react to something before it happened.

Had a moment of realizing just how wild it is the fact that eyes are a thing and are almost perfect for seeing the world around us. All that time for evolution so I can shitpost in HD is something else.

[Anonymous No.14701453]

Frens, can you help me with this.
Pic rel is how far I got.
Can you also explain why X1 (marked on pic) is wrong? Thanks.

[Anonymous No.14701480]

Can I simplify this circuit? I basically want 2 different LEDs to turn on at 2 different V2 voltage thresholds.

[Anonymous No.14701484]

>>14699392
I’m the person who posted this. I think I figured it out. Here’s the sketch.
Basically, if you identify S^2 with CP^1, then you can use the segre embedding to get a map from CP^1 x CP^1 to CP^3.
The image of this embedding satisfies a different relation than the one given in the problem, but I think you can diagonalize and it works out fine.
>>14700187
Thanks, but the square root symbol doesn’t actually give a well-defined function here. For the positive reals, it’s usually fine to just say “take the positive root”, but here, if you try to use a rule like that to make it work for all complex numbers, it won’t be continuous (or at least I personally can’t see a way to make this idea work)
tldr sqrt doesn’t work right with complex numbers

[Anonymous No.14701504]

>>14701453
Hope did you get the second line and where did the extra x come from?

[Anonymous No.14701598]

What textbook would cover this material for a "theoretical computer science" course?

What textbook would cover this material for a theoretical computer science course?

Mathematical Logic, Set Theory, and Graph Theory:

propositional logic, first order logic, proof techniques, mathematical induction, sets and set operations, relations and
operations on relations, functions, countable and uncountable sets, graph-theoretic concepts, such as graph
connectivity, graph isomorphism, trees, and Euler graphs.

[Anonymous No.14701625]

>>14701480
2 thresholds => 2 transistors. There may be a trick that would get rid of a resistor, but it hardly seems worth it and would probably make the circuit less robust (e.g. magnifying the effect of any variation in the LED voltage, reducing the threshold sharpness, or similar).

[Anonymous No.14701626]

The gearwheels are driven by V. Which wheel goes round fastest? (Not homework, taken from an intuitive physics test for autists)

[Anonymous No.14701642]

>>14701626
1. it doesnt matter which one is driving
2. in a gear train, the angular speed of a gear is inversely proportional to its radius. so W and Z would presumably be spinning the fastest.

[Anonymous No.14701655]

>>14701642
These are multiple choice answers in the form:
a) W
b) X
c) Y
d) Z

[Anonymous No.14701660]

>>14701655
iunno man just pick one

[Anonymous No.14701672]

>>14701660
Why would the test say W is correct but not Z?

[Anonymous No.14701680]

>>14701625
There's no way to make it work with a triple voltage divider like this?

[Anonymous No.14701685]

>>14701504
Conjugate to rationalize the radical in the numerator.

[Anonymous No.14701702]

>>14701672
Because Z isn't correct. That anon is retarded. Z is reduced by the presence of Y.
The total gear ratio is the PRODUCT of all intermediate ratios.

[Anonymous No.14701728]

>>14701702
i wouldnt call me retarded if i were you

[Anonymous No.14701748]

>>14701702
Could you express the speeds of W and Z as an equation with variables?

[Anonymous No.14701755]

>>14701680
The base of Q8 will never get above ~0.7V so Q9 will probably never turn on.

[Anonymous No.14701757]

>>14701504
Rationalizing by using conjugation

[Anonymous No.14701764]

Are 16 credits too little? I'm on a undergrad research, a club, and I thought of getting an internship next semester, but I wouldn't be able to take more than 3 subjects

[Anonymous No.14701772]

>>14701626
Whichever of W or Z has the smaller radius. Note that W rotates clockwise, Z anti-clockwise.

In a chain of connected gears, all gears have identical linear speed at their circumference, with the direction alternating. So r1·ω1=-r2·ω2=r3·ω3=-r4·ω4=...., |ωN/ω1|=r1/rN. The sizes of intermediate gears don't matter. The last gear rotates in the same direction as the first if there are an odd number of gears (including the first and last) and the opposite direction for an even number.

[Anonymous No.14701773]

>>14701672
W would spin faster if the gears were smooth or didn't perfectly fit because some of the friction bleeds off.
>>14701702
Don't call him retarded.

[Anonymous No.14701816]

>>14701772
I thought this was correct as well and verified it with this applet:
https://geargenerator.com/#200,200,100,6,0,4,0,5,1,8,2,4,20,0,0,0,0,0,0,0,10,2.5,4,20,0,0,0,0,0,1,0,16,4,4,20,0,0,0,0,0,2,0,4,1,4,20,0,0,0,0,0,1,0,4,1,4,20,0,0,0,0,0,0,1,3,864
But the test says only W is the correct answer.

[Anonymous No.14701856]

>>14701816
I think it is only W because X is smaller and with less teeth than Y so even though W and Z are the same size they will spin at a different speed.

[Anonymous No.14701871]

>>14701764
To some people 16 is too much. Most of my engineering friends refuse to take 5+ STEM classes a semester for workload and you have a research on top of that, so if your school is piss easy then maybe it's no problem.

[Anonymous No.14701887]

Is there any /sci/ archive with search enabled? Why the fuck do these sites even disable the fucking search?

[Anonymous No.14701924]

>>14701887
warosu

[Anonymous No.14701933]

>>14701887
Search is pretty resource intensive and the current tech stack behind archives fucking sucks.

[Anonymous No.14702035]

If the heart is such a strong muscle why isn't the whole body made of heart?

[Anonymous No.14702045]

>>14701453
>Can you also explain why X1 is wrong?
it looks like you squared both sides of the equation and then made the assumption that [math] (a - b)^2 = a^2 - b^2 [/math] which is not true generally.

You've got the right idea to square both sides of the equation to reduce the number of radicals, you just need to be a little more careful to make sure you are not making invalid assumptions

[Anonymous No.14702051]

>>14701933

[Anonymous No.14702103]

https://www.youtube.com/watch?v=FJRIg-HCy7g

[Anonymous No.14702392]

Two related Physics/cosmology questions:
First, is there a name for that one future scenario when all local galaxies fuse into a big supercluster, while all far galaxies drift away beyond the light boundary, so they're essentially undetectable by any means?
Second, what if the same kind of scenario has already happened in the past, where there was some sort of "particle boundary" for say, dark matter not being dark or primordial tachyons not flying beyond, just to name something, which makes them virtually undetectable and untestable beyond some point? Would it be 100% impossible to know or will there be some sort of inscrutable gap that at least tells you something's missing?

>>14667362
No, it's an umbrella term like the other Anon from /wsr/ said. It's synonymous to a paraphyletic clade, like "fish" which includes any vertebrate that swims and lives in water except for mammals, reptiles, amphibians, birds, etc.

[Anonymous No.14702400]

>>14702392
>is there a name for that one future scenario when all local galaxies fuse into a big supercluster, while all far galaxies drift away beyond the light boundary, so they're essentially undetectable by any means?
Heat death of the Universe or Big Freeze.

[Anonymous No.14702401]

>>14689399
Would this board or /g/ be better for the discussion of machine learning?

[Anonymous No.14702411]

>>14691153
Under the Jewish definition, please

[Anonymous No.14702545]

>>14701702
> Z is reduced by the presence of Y.
No it isn't.
> The total gear ratio is the PRODUCT of all intermediate ratios.
While true, that completely misses the point. Each diameter other than the first and last occurs in two ratios: once as the numerator, once as the denominator. The two cancel. The overall ratio depends only upon the diameters of the first and last gears. (A/B)(B/C)(C/D) = A/D.

>>14701748
>Could you express the speeds of W and Z as an equation with variables?
ωX/ωV = -rV/rX => ωX = -ωV(rV/rX)
ωW/ωX = -rX/rW => ωW = -ωX(rX/rW) = ωV(rV/rX)(rX/rW) = ωV(rV/rW)
ωY/ωX = -rX/rY => ωY = -ωX(rX/rY) = ωV(rV/rX)(rX/rY) = ωV(rV/rY)
ωZ/ωY = -rY/rZ => ωZ = -ωY(rY/rZ) = -ωV(rV/rY)(rY/rZ) = -ωV(rV/rZ)
Summary:
ωW = ωV(rV/rW)
ωZ = -ωV(rV/rZ)
If rW=rZ, then ωW=-ωZ, i.e. they have the same speed. The directions are always opposite because there are an odd number of gears between V and W (V,X,W) and an even number of gears between V and Z (V,X,Y,Z).

[Anonymous No.14702789]

>>14689399
How does quantum physics relate to causality? What if I, for example, set up an optical resonator that had a potential barrier in the middle and gain media on either side, such that a small number of photons would tunnel through the barrier during each pass and the signal would be amplified by the gain media for the next pass. Do the photons tunnel instantly? This is what I was taught in my undergrad classes and if that's the case I don't understand why you couldn't use something like this to technically send a signal faster than light.

[Anonymous No.14702849]

If independent voltage sources provide a specified current independent of the current flowing through it, then why are they exempt from Ohm's law?

[Anonymous No.14702882]

was this

[Anonymous No.14702893]

>>14702882
an unreasonable answer to this (part b)? my instructor is implying i was cheating and is threatening with a 0 for the assignment

[Anonymous No.14702917]

how do psychology researchers who do human experiments deal with people who are actively trying to figure out what the experiment is and outsmart it? I feel like a lot of people would try this bullshit and it'd ruin the results since they aren't acting naturally

[Anonymous No.14703044]

>>14702789
> Do the photons tunnel instantly?
It is believed to be instantaneous but it's a very difficult thing to actually measure. There's also the fact that at the quantum scales involved it is tricky to even define a "tunnelling time" due to the uncertainty principle - you don't know precisely the location of the incoming photons so can't accurately define a final velocity. So it may seem like FTL has occurred but all measurements show that causality is unaffected.

[Anonymous No.14703054]

>>14702849
Because they aren't Ohmic conductors. Ohm's law is a description of the behaviour of a wide range of materials, namely that current density is proportional to the electric field. It isn't an inviolable law of nature.

[Anonymous No.14703156]

>>14697434
x and y is the amount of tank A and B that is going to be mixed respectively. The concentration of a mixed solution is the sum of the solute divided by the volume of the solvent.
[math] \frac{64x+12y}{x+y} = 34 [/math]
[math] 64x+12y=34x+34y [/math]
[math] 30x=22y [/math]
[math] \frac{x}{y} = \frac{11}{15} [/math]

[math] \frac{x}{60} = \frac{11}{15} [/math]
[math] x = 44 [/math]
So if you have 60 gallons of tank B then you would need 44 gallons of tank A.

[Anonymous No.14703391]

>>14689399
in 1st order and 2nd order logic(consider this question asked separately if they have separate answers), is it necessary to categorize domain explicitly, or can you use predicates? For instance, I might say ∀(x)(Mx Ox), to say "For all X, if x is a man, x is mortal", and have to specify that I'm speaking in the domain of living creatures. Could I not always rephrase that to be ∀(x)(Cx ∧ Mx Ox) To mean for all x, if x is a creature, and x is a man, then x is mortal?

[Anonymous No.14703546]

Small questions about complex Numbers, I hope someone can quickly answer this to me because of my exam in a few hours.

Given the following:

[math] \sqrt{-2i} = \sqrt{2} * \sqrt{-i} = \sqrt{2} e ^{ \frac{2\pi}{n} + \frac{\phi}{n} } [/math]

I know that n = 2 because of square root.

1. why is [math] \phi = \frac{3\pi}{4} [/math] and not [math] \frac{\pi}{4} [/math] or at least [math] - \frac{\pi}{4} [/math] because of -i
2. How do you know without radiant and just seeing either (1/0) or (0/3i) to which quadrant this thing belongs?
3. How do you change the above formula if it’s -i , -1 etc.

Generally my problem is mostly finding phi for a=0 or b=0, like tan(0) doesn’t work

[Anonymous No.14703569]

Should I start a physics degree at 27? I have the time.

[Anonymous No.14703604]

>>14702045
Thank you for helping me, fren. I finally did it by using pic related method. I'll try to redo the sum using the first method and see where if I can do it.

[Anonymous No.14703613]

>>14703604
But doing it this way gets me a wrong answer. Where did I mess up here?

[Anonymous No.14703628]

>>14703613
Why not just square and just take the square root of x

[Anonymous No.14703644]

Why is the underlined equality true?

[Anonymous No.14703659]

>>14697310
>somehow I don't know energy
Alright, consider the following two facts:
1. stable compounds are low in energy (hence why energy is required to break them apart)
2. stable compounds are hard to extract energy from due to their stability
Carbon dioxide is a stable compound that further has low solubility (hence why it's not in rain water). Because of how laborious of an effort it would be to remove from the atmosphere (compared to, say, sulfur dioxide), it'd be more advantageous to reduce emissions in the long run, which is far easier than dealing with the consequences of high CO2 emissions.
Read this for more http://libgen.is/book/index.php?md5=8BB88AB108B2254CBCA38B080483576B
Your earthquake ideas are rather unrealistic/far too difficult to implement. Read this for an overview of modern seismology http://libgen.is/book/index.php?md5=9BC2B855965EE4D977C22FC733D9A22A
part 2: http://libgen.is/book/index.php?md5=27E095EFE2F4D5B098C12A66D76727ED

[Anonymous No.14703664]

>>14703644
Nvm got it.

[Anonymous No.14703695]

I'm stuck, can someone give me a hint?

[Anonymous No.14703805]

>>14703695
[math]R_2 \circ R_1 = \Delta_X[/math] implies that for every [math]x \in X[/math] there is at least one [math]y \in Y[/math] with [math](x,y) \in R_1[/math] and [math](y,x) \in R_2[/math].

Now for a [math]x \in X[/math] take any two [math]y_1,y_2 \in Y[/math] with [math](x,y_1),(x,y_2) \in R_1[/math] and [math](y_1,x),(y_2,x) \in R_2[/math].
Then [math](y_1,y_2) \in R_1 \circ R_2[/math] since [math](y_1,x) \in R_2[/math] and [math](x,y_2) \in R_1[/math] but [math] R_1 \circ R_2 = \Delta_Y[/math] so [math]y_1 = y_2[/math].
This implies that for every [math]x \in X[/math] there is at exactly one [math]y \in Y[/math] with [math](x,y) \in R_1[/math] and [math](y,x) \in R_2[/math].
By the symmetric arguement you also get that for every [math]y \in Y[/math] there is at exactly one [math]x \in X[/math] with [math](x,y) \in R_1[/math] and [math](y,x) \in R_2[/math].

[Anonymous No.14703826]

how/why does e = mc^2 not need a constant to adjust it if the units were not chosen in the first place to make them fit? if any of the units specified any other value, wouldn't it need adjustment?

[Anonymous No.14703881]

Is there an efficient way to get a matrix that belongs to a pair of similar matrices? So
[math]A = XBX^{-1}[/math]
I've figured out that I can get it if I diagonalize both matrices because
[math]A = PDP^{-1}[/math]
[math]B = RDR^{-1}[/math] -> [math]D = R^{-1}BR[/math]
[math]A = PR^{-1}BRP^{-1}[/math]
[math]X = PR^{-1}[/math]
But that's time consuming so I'm wondering if there's some simpler way?

[Anonymous No.14703906]

My pirated version of Endnote has been rumbled. The small number of alternative keys I have is not working.
Anyone able to help / know a source of other keys?

[Anonymous No.14704063]

>>14703826
> if the units were not chosen in the first place to make them fit?
They were. That's why we have the S.I. units.

Also I think you are getting confused between "units" and "dimension". Energy has the dimensional form of [math]M^1 L^2 T^{-2}[/math] but the value is defined by whatever units you use.

[Anonymous No.14704371]

How necessary are proof books for "mathematical maturity"? Currently reading through an elementary analysis book and I wonder, since nearly every other exercise involves proving stuff, and I will be proving much, much more the next few years, if a book specifically on proofs would even be necessary? They seem pretty useless to me since it see. Should I just read a book on propositional logic or so?

[Anonymous No.14704382]

>>14704371
meant to say since I feel like getting exposed to a large variety of proofs will supply you with lots of proving strategies that would nullify such boos

[Anonymous No.14704399]

>>14703805
Thank you very much. This absolutely answers my question.

[Anonymous No.14704531]

what's a good open source software to draw science diagrams, physics ones in particular.
I've been using krita and screenshotting latex equations but it doesn't look very professional. I don't mind if I have to use commands like in latex as long as it isn't pure autism

[Anonymous No.14704538]

>>14704531
I usually use inkscape and then export it as a pdf and include it as a graphic in LaTeX. This has the added benefit of text being selectable.

[Anonymous No.14704747]

>>14703613
line 6 is wrong, you can't just drop the radicals like that, the only way to get rid of the radicals is to square both sides but you omitted the [math] -2 \sqrt{(x+1)(x-4)} [/math] from the right side of the equation

[Anonymous No.14705024]

can someone help me, I got the characteristic equation for v1(t), but I can't figure out v1(0), and v1'(0). I think v1(0) should be 0 since there's no voltage across the circuit until it's turned on, but for v1'(0) would the current through the first resistor be 20A since the source is turned on, and the node voltage at v1 is 0, so all the current would flow directly through the 0.5F capacitor?

[Anonymous No.14705051]

Why isn't kinetic energy considered one of the fundamental forces of the universe?

[Anonymous No.14705086]

>>14704531
tikz in latex
inkscape is supposed to be good too if you want something less autistic

[Anonymous No.14705101]

>>14704747
Finally solved it. Thank you so much fren!
>>14703628
I did. But wanted to figure out what went wrong doing it this way.

[Anonymous No.14705105]

>>14705051
because it's not a force

[Anonymous No.14705118]

Testing something real quick.

[Anonymous No.14705256]

>>14705105
>In Physics, force is defined as: The push or pull on an object with mass that causes it to change its velocity
Why not?Seems to fit the definition.

[Anonymous No.14705305]

Hi /sqt/ I have accepted an offer to start in Oct 22 in a top 10 uni in the UK (not Oxbridge) for Chemistry BSc. I previously took 1 year in Biochemistry BSc in a diff uni but dropped out due to mental health reasons (I was keeping up good with the course until my mental health hit the shitter). Can I get a tl;dr on best course of action in my undergrad degree and beyond (STEM related not social etc)? Sorry if this is a common or stupid question but I really have no clue what the fuck I'm doing or what's happening and feel like I'm missing something obvious like theres some shit i need to be doing but wasn't last year ?

[Anonymous No.14705331]

>>14705256
energy and force are two different things. kinetic energy doesn't cause an object to change velocity, it's a quantity that is dependent on velocity. you'll need a force to give said object a velocity and raise its kinetic energy.

[Anonymous No.14705355]

Is Atlantropa possible with our current technology and is it a viable project?

[Anonymous No.14705385]

Is there a latex command that creates a very basic environment for doing inline code? I don't need fancy formatting or highlighting, I just want white space and line breaks respected within some \begin{} .. \end{} brackets is all.

[Anonymous No.14705589]

>>14705385
\begin{verbatim} \end{verbatim}

[Anonymous No.14705716]

I have an electromagnetism question. I'm studying the force excerted on a dielectric slab partially inserted in a parallel plate capacitor (section 4.4.4 of Griffiths) and while I can follow his reasoning and find the force by taking the gradient of the energy, I have a few questions.

Griffiths says W=1/2*C*V^2, which we derived in an earlier chapter, and which we derived by assuming the field inside the capacitor was perpendicular to the plates and only existed between the plates. However Griffiths also says that the field responsible for the force excerted in the dielectric is a fringing field, which we did not consider for the calculation of W.

How then, can we say that F=gradient of W when W doesn't take into account the E that produces the force in the first place? Aren't we missing the energy stored in the fringing field?

[Anonymous No.14705804]

Is Brie the most popular french cheese or am I forgetting one?

[Anonymous No.14705817]

>>14705804
cute wemi <3
https://www.youtube.com/watch?v=Y8F-0Ogp4fU

[Anonymous No.14705852]

>>14705817
Sardinia isn't part of France.
>you can't sell it
>but that's because people are pussies it's still safe dude just trust me
Dubious.

https://en.wikipedia.org/wiki/Casu_martzu#Health_concerns
>According to some food scientists, it is possible for the larvae to survive the stomach acid and remain in the intestine, leading to a condition called pseudomyiasis. There have been documented cases of pseudomyiasis with P. casei.

[Anonymous No.14705861]

>>14705852
>Sardinia isn't part of France.
yeah, and maggot cheese isnt very popular. i just posted it because i thought it'd gross you out.

[Anonymous No.14705873]

>>14705861
I've eaten similar before.
I think you need to be sort of insane to actually eat that tho, humans have ingrained disgust reactions against food with living fucking maggots in it. I'd eat it for a dare but I wouldn't eat it for the heck of it.

[Anonymous No.14705891]

>>14705873
>I've eaten similar before.
thats fuckin nasty bro.

[Anonymous No.14706040]

Is this correct? theres alot of steps, just wanna know if i arrived at the right answer

[Anonymous No.14706043]

>>14706040
Did the dot product of F (after plugging in x,y,z) and dr then integrated the result

[Anonymous No.14706046]

>>14705873
id eat that shit, just take the bugs out lol. i dont subscribe to the idea that the bugs just jump out when you take a bite

[Anonymous No.14706093]

>>14706046
>id eat that shit
literally. the bugs themselves are only half the concern, anon...

[Anonymous No.14706150]

>>14706040
I get 9/4

[Anonymous No.14706176]

probability distributions indicate the relative frequencies of outcomes of events
given that they are graphs of frequencies, what would the inverse fourier transform of a probability distribution represent

[Anonymous No.14706300]

Why is distributive a property instead of a theorem? It follows from associative law.

[Anonymous No.14706338]

>>14706300
>It follows from associative law.
That is simply false for general algebraic structures

[Anonymous No.14706388]

>>14706300
Consider the space of functions from [math]\mathbb{R}[/math] to [math] \mathbb{R}[/math].
You have assotiativity for both addition and composition of functions.
[eqn](f + g) + h = f + (g + h) \\
(f \circ g) \circ h = f \circ (g \circ h)[/eqn]
for all [math]f,g,h \in \mathbb{R}^\mathbb{R}[/math]
But in general
[eqn]f \circ (g + h) \neq f \circ g + f \circ h [/eqn]

[Anonymous No.14706510]

If I study math for 4 hours a day, how many years would it take me to go from pre-algebra to arithmetic geometry?

[Anonymous No.14706712]

How do I go about solving this? I have no clue.

[Anonymous No.14706720]

>>14706712
x=(((2^2-2)^2-2)^2-2)^2-1

[Anonymous No.14706752]

>>14706712
√a = b => a = b^2
a+b = c => a = c-b
If the outermost operator is a square root, square both sides. If the outermost operator is an addition, subtract from both sides. Keep going until the LHS is just x.

[Anonymous No.14706775]

>>14706510
It's impossible to answer that question, everyone moves at their own pace.

[Anonymous No.14706846]

>>14706338
>>14706388
Idk man I’m just talking about simple numbers. Spivak’s calculus claims you can’t derive distributivity, from the other properties, but it follows straight away from associativity (for numbers)

[Anonymous No.14706931]

>>14706846
>but it follows straight away from associativity (for numbers)
Feel free to post a proof

[Anonymous No.14707336]

Are there any particles, waves, forces, etc, that can escape a black hole? What about quantum entanglement. If you entangle one thing with another and send one into a black hole can you communicate with the inside of the black hole? Also colliding protons creates a black hole? Why? It also causes the proton to split into lower particles? Are these entangled at all? Also how do you entangle particles or are they pre entangled in nature and just stay entangled together for life? Overall wondering how you might send something through a black hole and communicate with what's on the other side of it

[Anonymous No.14707374]

>>14707336
Nothing escapes a black hole. Entanglement just means a correlation between the state of one particle and the state of another particle. It can't be used to communicate.
You might be interested in https://backreaction.blogspot.com/2020/11/the-black-hole-information-loss-problem.html

[Anonymous No.14707406]

>>14707374
OK, tarded follow up. Isn't the electromagnetic radiation they reference just light? They make it sound like back holes emit this ans in doing so they shrink. But I thought this radiation doesn't have mass? And I thought mass never leaves black holes...? Also to clarify, the collision of protons does not emit anything, it just creates a black hole and splits the proton up? Also the text you linked didn't clarify the entanglement thing. So you cannot entangle through a Blakc hole? I am pleb BTW. Braindog

[Anonymous No.14707646]

Is an ice age coming?

[Anonymous No.14707700]

Redpill me on stem cell therapy.
Is it promising or a bunch of bullshit?

[Anonymous No.14707777]

>>14689399
>how do I post math symbols (Latex)?
Why would you specifically capitalize the L but not the t and the x?

[Anonymous No.14707787]

How would you prove that any set can be represented as a union of equivalence classes of any equivalence relations on the elements of the set?

[Anonymous No.14707797]

>>14707646
Not anytime soon. The current interglacial is predicted to last for a while longer, plus we're heating the planet, so maybe this won't be an interglacial at all.

[Anonymous No.14707832]

Test.

[Anonymous No.14707839]

>>14707832
You did something wrong, I can see your IP address.

[Anonymous No.14707890]

>>14707797
We really do need to cool the planet.

[Anonymous No.14707898]

>>14707890
Why do you hate indigenous Canadians so much?

[Anonymous No.14707916]

>>14707787
That's absolutely trivial unless I'm missing something.
Let [math]X[/math] be the set and [math]\sim[/math] be an equivalence relation.
[eqn]X = \bigcup_{x \in X} \{x\} \subseteq \bigcup_{x \in X} [x]_\sim[/eqn]
since every element is part of it's own equivalence class and
[eqn]\bigcup_{x \in X} [x]_\sim \subseteq X[/eqn]
since every equivalence class is a subset of [math]X[/math] its union must be one too.

[Anonymous No.14707957]

>>14707916
>That's absolutely trivial unless I'm missing something.
It's trivial.

[Anonymous No.14708010]

>>14707777
Even that is not enough: [math] \mathrm{\LaTeX}[/math]

[Anonymous No.14708044]

>>14706931
Just do a general example and see it follows straight away from associativity.
[eqn] x(a+b) = (a + b) + (a + b) + \cdots[/eqn]
There are [math] x[/math] number of [math](a+b)[/math] terms, therefore by associativity, we can just group the [math] a[/math]'s together, and same for [math] b[/math], and hence we get [math] ax + bx[/math]
>inb4 but but muh that is not rigorous
Isn't that literally how it's proved that: [math] (ab)^x = a^x b^x[/math].

[Anonymous No.14708084]

>>14708044
So if [math]x = -\pi[/math] then
[math] x (a+b) = (a+b) + (a+b) + \ldots[/math] until you reach [math]- \pi[/math] terms???

[Anonymous No.14708226]

my book says x^n mod m =
(x^(n-1)modm*xmodm)modm

dont all these extra mod m's do nothing? like 2%m%m is just 2%m isnt it

why not just write as (x^(n-1)*x)modm?

[Anonymous No.14708255]

>>14708044
> x(a+b) = (a + b) + (a + b) + ...
You're relying upon distributivity here.

You might be talking about numbers, Spivak isn't. You're essentially relying upon having a definition for multiplication which asserts distributivity, e.g.:
0·x = 0
(n+1)·x = n·x+x
When dealing with abstract algebras, you don't have this.

[Anonymous No.14708269]

>>14707898
why don't you?

[Anonymous No.14708619]

>>14708226
maybe it's useful for a proof of some sort
give some context

[Anonymous No.14708628]

>>14708044
>Isn't that literally how it's proved that:
Not really.
[math](ab)^x = \exp (x \log ab) = \exp (x (\log a + \log b)) = \exp (x \log a) \exp (x \log b)[/math]
>>14708226
Your book is doing some sort of mess where [math]\mod m: \mathbb{Z} \to \{ 0, 1, \ldots, m - 1 \}[/math], isn't it?

[Anonymous No.14708689]

>>14708628
oh yes i looked on the chapter where it talks about "arithmetic modulo m" and arrithmetic operations on Z(subscript m), the set of nonnegative integers less than m

but then it mentions commutative groups and commutative rings and +(subscript m) and *(subscript m) and it loses me

the book is an introductory discrete math book

[Anonymous No.14708920]

>>14708226
The point is that you can take the residue modulo m at each step.

(a+b)%m = ((a%m)+(b%m))%m
(a*b)%m = ((a%m)*(b%m))%m
(a^b)%m = ((a%m)^b)%m

This is fairly important if you're performing calculations where intermediate terms could become infeasibly large. E.g. calculating (x^y)%m for large x,y.

Note that it doesn't hold for division, i.e. (a/b)%m ≠ (a%m)/(b%m), but you normally define division as multiplication by the reciprocal for modular arithmetic. a/b = a.b^-1 where b^-1 is defined by b.b^-1≡1 (mod m).

[Anonymous No.14709294]

>>14706720
>>14706752
Thank you. You guys are so kind.

[Anonymous No.14709303]

Whenever a lecturer shows us how we arrive at a formula my brain just switches off, and it seems real difficult to understand whats going on. Is that normal or am I just dumb? Why do they show us this stuff when we're learning it for the first time? All it seems to do is confuse.

[Anonymous No.14709656]

>>14689399
How can I prove: [eqn] \forall x\in\mathbb R \quad \forall a,b \in \mathbb Z \quad (x^a)^b = x^{ab}[/eqn] if I cannot use the property: [math] x^a x^b = x^{a+b}[/math]

[Anonymous No.14709660]

>>14709656
[math] b > 0[/math]

[Anonymous No.14710424]

>doing nonlinear constrained optimization problem with MATLAB's fmincon
>provide constraint jacobians to speed things up
>optimization performs worse (no convergence)
I'm 100% sure the jacobians are correct and the optimizer confirms they're correct too. How can an optimizer do worse with jacobians than without jacobians?

[Anonymous No.14710502]

hej friends r-slur here
been out of school for 6 years and remember 0 basic math and I'm taking a calculus course to get an admission credit for college atm and I can't for the fucking life of me figure out how to factor things
[math]\frac{3x^{2}-2x-1}{x-1}[/math] = [math]\frac{(3x+1)(x-1)}{x-1}[/math]
this is an example from the course I'm taking and I genuinely can't comprehend how the hell to get from the left equation to the right
he doesn't explain in the lecture I'm assuming because it's so basic I should know it but I don't
could someone explain this in retard terms or point me somewhere that would do so

[Anonymous No.14710542]

>>14710424
Does fmincon uses the same algorithm for both? I also expect analytical derivatives to be more accurate. But maybe your function is unusual. Maybe it has an analogy with Weierstrass function. Rather than binary existence we have truncation or rounding error. The finite differences depend on continuity while jacobians depend on differentiability. In other words, the analytical derivatives might be much larger in some places and this sends the search farther in the wrong direction.

[Anonymous No.14710553]

>>14710502
You can write a polynomial as a product of (x-a) where a is a zero of the polynomial.
Example [math]3x^2-2x-1=x^2-\frac{2}{3}x-\frac{1}{3}[/math]:
[math]x_{1,2}=\frac{1}{3}\pm \sqrt{\frac{1}{9}+\frac{1}{3}}=\frac{1}{3}\pm\frac{2}{3}\\\rightarrow x_1=1,x_2=-\frac{1}{3}\\\rightarrow 3x^2-2x-1=(x-1)(x+\frac{1}{3})[/math]
You can then multiply by 3 to get your answer

[Anonymous No.14710556]

>>14710553
fucking latex
[eqn]x_{1,2}=\frac{1}{3}\pm \sqrt{\frac{1}{9}+\frac{1}{3}}=\frac{1}{3}\pm\frac{2}{3}\\
\rightarrow x_1=1,x_2=-\frac{1}{3}\\
\rightarrow 3x^2-2x-1=(x-1)(x+\frac{1}{3})[/eqn]

[Anonymous No.14710579]

>>14710502
If you have a polynomial [math]p(x) \in \mathbb{C}[x] [/math] with a degree of at least 2 then all you need to is to find a root of the polynomial. That is a number [math]r \in \mathbb{C}[/math] such that [math]p(r) = 0[/math], Then you can factor the polynomial into
[eqn]p(x) = (x - r) q(x) [/eqn]
where [math]q(x)[/math] is a polynomial with a degree 1 less than [math]p(x)[/math]. To explicitly calculate [math]q(x)[/math] you can just use long division ass [math]q(x) = \frac{p(x)}{x - r}[/math].
If the degree of [math]q(x)[/math] is still at least 2 then you can repeat this process again for [math]q(x)[/math] each time removing one linear factor until you have fully factored everything.

That is if you're only dealing with polynomial whose coefficient are complex numbers or any other complete field. If you have polynomials with over any other ring it can be very difficult to determine whether or not they can be factored at all.

[Anonymous No.14710618]

>>14710553
>>14710556

[Anonymous No.14710655]

>>14710553
>>14710579
thanks lads
just got out of a tutoring session for the same thing and between that and these I think I might actually be able to grasp it
I actually feel braindead doing math and it's making me reconsider if I'll even get through school to get a degree

[Anonymous No.14710657]

>>14710618

[Anonymous No.14710701]

>>14710657
Add space after [eqn]. You should know this by now.

[Anonymous No.14710769]

Any medanons here, is it dangerous to put olive oil in your ear to treat earwax? Idk if it can damage the eardrums if you let it go to deep or something. Google isn't helping

[Anonymous No.14710773]

>>14710701
[eqn]x_{1,2}=\frac{1}{3}\pm \sqrt{\frac{1}{9}+\frac{1}{3}}=\frac{1}{3}\pm\frac{2}{3}\\
\rightarrow x_1=1,x_2=-\frac{1}{3}\\
\rightarrow 3x^2-2x-1=(x-1)(x+\frac{1}{3})[/eqn]
well I didn't

[Anonymous No.14710774]

>>14710769
just use hydrogen peroxide why would you put olive oil in your ear?
t. narrow ear canals and have to clean my ears frequently

[Anonymous No.14710776]

>>14710773
[eqn] x_{1,2}=\frac{1}{3}\pm \sqrt{\frac{1}{9}+\frac{1}{3}}=\frac{1}{3}\pm\frac{2}{3}\\
\rightarrow x_1=1,x_2=-\frac{1}{3}\\
\rightarrow 3x^2-2x-1=(x-1)(x+\frac{1}{3})[/eqn]
wrong eqn fuck me

[Anonymous No.14710826]

>>14710542
I'm not sure but maybe you're right. It's a shame because my problem takes a while to solve and I hoped providing jacobians would speed things up. At least MATLAB has parallelization support. I wonder if I can get considerable speed gains with FORTRAN or if I'll just waste time trying to shave off a few seconds.

[Anonymous No.14710966]

>>14710776
Just upload a standalone pdf at this point.

[Anonymous No.14710972]

>>14710776
[eqn]
x_{1,2}=\frac{1}{3}\pm \sqrt{\frac{1}{9}+\frac{1}{3}}=\frac{1}{3}\pm\frac{2}{3}
[/eqn]
[eqn]
\implies x_1=1,x_2=-\frac{1}{3}
[/eqn]
[eqn]
\implies 3x^2-2x-1=(x-1)(x+\frac{1}{3})
[/eqn]

[Anonymous No.14710991]

>>14710776
test
[eqn] x_{1,2} = \frac{1}{3} \pm \sqrt{ \frac{1}{9} + \frac{1}{3} } = \frac{1}{3} \pm \frac{2}{3} \\
\implies x_1 = 1, \quad x_2 = - \frac{1}{3} \\
\implies 3 x^2 - 2x - 1 = ( x - 1 ) ( x + \frac{1}{3} ) [/eqn]

[Anonymous No.14710997]

>>14710553
>>14710556
>>14710618
>>14710657
>>14710773
>>14710776
Add space before every backslash

%[eqn]
x_{1,2} = \frac{1}{3} \pm \sqrt{ \frac{1}{9} + \frac{1}{3} } = \frac{1}{3} \pm \frac{2}{3} \\
\implies x_1 = 1, \quad x_2 = - \frac{1}{3} \\
\implies 3 x^2 - 2x - 1 = ( x - 1 ) ( x + \frac{1}{3} )
%[/eqn]

[Anonymous No.14711002]

>>14710997
[math] \text{ }^{\color{#511da7}{\displaystyle\text{w}}}\text{ }^{^{^{\color{#4136c0}{\displaystyle\text{h}}}}}\text{ }^{^{^{^{^{^{\color{#3e56cd}{\displaystyle\text{a}}}}}}}}\text{ }^{^{^{^{^{^{^{^{^{\color{#4274cd}{\displaystyle\text{t}}}}}}}}}}}\text{ }^{^{^{^{^{^{^{^{^{^{^{\color{#4b8dc1}{\displaystyle\text{'}}}}}}}}}}}}}\text{ }^{^{^{^{^{^{^{^{^{^{^{^{^{\color{#57a0ad}{\displaystyle\text{s}}}}}}}}}}}}}}}\text{ }^{^{^{^{^{^{^{^{^{^{^{^{^{^{\color{#66ae94}{\displaystyle\text{ }}}}}}}}}}}}}}}}\text{ }^{^{^{^{^{^{^{^{^{^{^{^{^{^{^{\color{#78b67c}{\displaystyle\text{u}}}}}}}}}}}}}}}}}\text{ }^{^{^{^{^{^{^{^{^{^{^{^{^{^{^{^{\color{#8ebb66}{\displaystyle\text{p}}}}}}}}}}}}}}}}}}\text{ }^{^{^{^{^{^{^{^{^{^{^{^{^{^{^{\color{#a5bd55}{\displaystyle\text{ }}}}}}}}}}}}}}}}}\text{ }^{^{^{^{^{^{^{^{^{^{^{^{^{^{\color{#bbbb48}{\displaystyle\text{b}}}}}}}}}}}}}}}}\text{ }^{^{^{^{^{^{^{^{^{^{^{^{^{\color{#cfb440}{\displaystyle\text{i}}}}}}}}}}}}}}}\text{ }^{^{^{^{^{^{^{^{^{^{^{\color{#dea53b}{\displaystyle\text{t}}}}}}}}}}}}}\text{ }^{^{^{^{^{^{^{^{^{\color{#e58e36}{\displaystyle\text{c}}}}}}}}}}}\text{ }^{^{^{^{^{^{\color{#e56e30}{\displaystyle\text{h}}}}}}}}\text{ }^{^{^{\color{#df4828}{\displaystyle\text{e}}}}}\text{ }^{\color{#da2121}{\displaystyle\text{s}}}[/math]

[Anonymous No.14711039]

>>14710997
thanks anon
fucking moot

[Anonymous No.14711266]

>>14709656
What properties *can* you use?

[Anonymous No.14711313]

>>14710502
3x^2-2x-1
You can find the roots using the quadratic formula; this can then be factored as 3(x-a)(x-b) where a,b are the roots. But I suspect you're expected to be able to factor this by inspection. The sum of the coefficients (3,-2,-1) is zero, so x=1 is a root and thus x-1 is a factor. 3x(x-1) = 3x^2-3x. 3x^2-2x-1 = 3x^2-3x + x-1 = (3x+1)(x-1).

More generally, (ax+b)(cx+d) = acx^2+(ad+bc)x+bd. In this case, you have ac=3, bd=-1. ac=3 => a=3, c=1 (the alternative, a=1, c=3 just swaps the two factors so can be ignored). So you have (3x+p)(x+q) = 3x^2+(p+3q)x+pq = 3x^-2x-1 => pq=-1 => p=1, q=-1 or p=-1, q=1. p+3q=-2 => p=1, q=-1 is the correct option, i.e. (3x+1)(x-1). For polynomials with integer coefficients, you start by factoring the first and last coefficients.

[Anonymous No.14711421]

>>14689399
taking physics for the first time and most of the time im just accepting things for what they are just to keep up for now.

But not being able to understand anything is frustrating to me and my teacher is not the type to answer questions. So i feel like i should ask my stupid questions here. My question right now is how equations are created . For example for ke= mv^2 , how does one know velocity needs to be squared, how do you know mass needs to be multiplied instead of added?

[Anonymous No.14711443]

>>14711421
Work/Energy is force times displacement.
Then you do some substitutions depending on the force you're looking at.
Units have to work out.

[Anonymous No.14711446]

>>14711266
Anything that’s in chapter 1 of Rudin

[Anonymous No.14711467]

Anons, how does this sum work?

Where does the -1 go in the sum index bound?

I struggle so much with sums and manipulating the index

[Anonymous No.14711483]

>>14711467
try using some actual numbers and a simpler expression and you will see why the manip works

[Anonymous No.14711491]

>>14711467
You need to change both bounds if you manipulate the index.The highest value for [mat]k[/math] is [mat]n-i-1[/math].
Using the new index, [math]k'=k+1[/math], the highest value for [math]k'[/math] is [math]k_{max}' = k_{max} + 1 = (n-i-1)+1 = n-i[/math].

[Anonymous No.14711643]

>>14711443
look i get the units part but how did the person who created the equation know where to put the pieces

[Anonymous No.14711668]

>>14711643
It took a shitload of time to figure it out.
I think it was mostly empirical.
Also, 'how did they do it' is usually harder to understand than what they actually did.

[Anonymous No.14711687]

>>14711491
>>14711483
ty anons this makes sense to me now, what about the bottom sum?

why does adding ai to the sum bring the lower bound down to k=0?

since its ai not a0 why do we get to say that ai is the 0th term and decrement k to 0. why didnt it bring the top bound to n-i-1 or something instead?

[Anonymous No.14711717]

>>14711687
>why does adding ai to the sum bring the lower bound down to k=0?
Because [math]a_i x^0[/math] happens to fit as a term of the sum for the index [math]k=0[/math], so we can integrate it into the sum and change its lower bound appropriately.

[Anonymous No.14711738]

>>14711717
okay tyvm, i am going to try and do some extra exercises just for sums so i can stop hitting a wall every time i encounter one

[Anonymous No.14711779]

>>14709656
but you can use the property. prove it if you have to.

[Anonymous No.14711785]

What's the point of cohomology if it encodes the same information as homology? Is it easier to compute?

[Anonymous No.14711801]

why can't I imagine a new color?

[Anonymous No.14711805]

>>14711668
understood

[Anonymous No.14711816]

>>14711801
humans are hardwired for inductive reasoning. Humans use past experiences to attempt to predict a future outcome. So you cant imagine a completely new color without having past sensory experience of it. Same reason why a blind person cannot describe what properties wood has.

[Anonymous No.14711819]

>>14711816
correction, i meant to say a blind person cannot describe what color wood is, a blind person can definitely describe other properties however

[Anonymous No.14711823]

>>14664565
aren't all the eigenvalues for a porjection matrix just 1s and 0s?

[Anonymous No.14711837]

Does there exist a scale (like for measuring mass) precise enough to detect a beam of light shining onto it? Obviously that beam produces a force so in theory it's possible. I guess it's a tech question.

>>14711823
Yes. Easily verifiable:
>Pv=rv for some vector v and scalar r
>hence rv is in the subspace
>hence v is in the subspace or r=0
>so rv=Pv=v or Pv=0

[Anonymous No.14712038]

>>14709303
The latter.
>Why do they show us this stuff when we're learning it for the first time?
So you can actually understand things without just knowing them by heart.
>>14710424
>How can an optimizer do worse with jacobians than without jacobians?
Shit man the geometry behind this is too basic to actually explain.
A non-constrained problem can go straight to the minimum, a constrained problem can take retarded, tortuous paths.
Or vice versa.
>>14711837
>Does there exist a scale (like for measuring mass) precise enough to detect a beam of light shining onto it?
IIRC the fact that light could cause measurable force was part of Einstein's empirical evidence for relativity and for light having momentum in spite of having no mass.
>>14711785
>it encodes the same information as homology
It doesn't necessarily.
But if I had to give a single main point then it's "cohomology ring".

[Anonymous No.14712119]

>>14711801
well i mean you can, i'm doing it right now.

[Anonymous No.14712172]

>>14712119
why i have just now imagined the color bellow.

what is bellow you ask? just overlay blue and yellow on top of each other. its not green, dont overlay it that way, overlay it with your mind and see them both at the same time.

bellow is a lot like greed, which is what you get when you overlay green and red. not yellow, use your imagination, come on. imagine green and red on top of each other.

Please tell me you can at least imagine hyper green?

[Anonymous No.14712232]

>>14712172
https://coub.com/view/d7av2

[Anonymous No.14712261]

>>14711785
Homology and cohomology are dual. Most cohomology theories arise as the dual of a homology theory and are hence "richer" the same way the dual of any vector space can he a more complex object than the original space. They don't encode the same information.

[Anonymous No.14712302]

>>14689399
Help. The boundary conditions are T at R1=T1 and T at R2=T2

[Anonymous No.14712369]

It's correct to clear the 'y' like this

[Anonymous No.14712373]

>>14712369
as long as it's [math]\pm\sqrt{x}[/math]

[Anonymous No.14712379]

>>14712369
It can be correct to take the square root of both sides, as long as you keep track of positive and negative signs properly.
But this image seems to imply that you’re multiplying both sides by root 1, then maybe dragging out the radical sign or something? That’s not how it should work

[Anonymous No.14712426]

>Taking the equivalent of a high school maths course to revise because it's been over a decade
>Just went over index and log laws
>These are our assigned practice questions
what the hell man I barely know how to do any of these without looking at the solutions. How would I know you're supposed to assign 3^x its own variable in 3e

[Anonymous No.14712440]

>>14712426
You can, of course, use the log or exponent of a different base too. [math]e[/math] is used often just because it's defined in a way that is convenient in analysis.

[Anonymous No.14712484]

>>14712440
I meant the question 3e sorry

[Anonymous No.14712501]

>>14712484
no, it's my fault for not reading your comment carefully. I can only say that substitution is very common and by doing a variety of such exercises, you will start noticing possible substitutions fairly quickly. Outside of solving ridiculous integrals, the substitutions themselves are usually not far more complex than that. Use it again and again in the next few days, weeks, etc. and you will develop intuition for it., I'm sure.

[Anonymous No.14712680]

>>14712501
Alright, I guess practice is the main thing. It's not terribly difficult I suppose, I'm just frustrated by the difficulty of the questions since we've just been introduced to the topic

[Anonymous No.14713199]

>>14712680
Yeah but remember that all of math is like that. There isn't a single mathematician who claims math is "easy" and the people who are struggling with math the most are top mathematicians working in research. Every single time I open a book on a new topic in math I first have to struggle a lot for some days until I develop some basic intuition that then gets stronger and stronger. Borcherds, a field medalist, said he spends around 10 hours a day thinking about research problems, developing thoughts, etc., that wind up getting scrapped, most of the time. Math is really just eternal learning and the people at the forefront are trying to make sense of cutting-edge stuff, like seemingly weird connections between large fields of math.

[Anonymous No.14713547]

I just need a theory gutcheck on this. It's from a practice problem I'm working on.
[math]K_n = .0005 \frac{A}{V^2}\\V_{TN} = 1.2 V\\\lambda = 0[/math]
We weren't really taught about current sources or how to interpret them in my intro to circuits class, but I've been using them on my own for years so I have some basic intuition for them.

I know from intuition that an ideal current source will generate whatever voltage is necessary to maintain its target current, regardless of quiescent conditions in the rest of the circuit.
So, the -5 volt supply is effectively invisible to the MOSFET as the current source is shielding the transistor circuit from the -5 volt source.

Solving for the values in the circuit, V_G = 0 (obviously), V_GS = 1.516. However, I don't see why V_DS = 5+1.5156 = 6.5156 volts.
The best I can come up with is that if the current source is acting as a "virtual ground" for the transistor circuit, and since there is no source resistor, then [math]V_{GS} = V_{DS}[/math] but I'm not sure how valid that is.

[Anonymous No.14713811]

Getting into electronics, and want to buy a lab power supply. In a lot of manuals for them I'm reading that to set the current limit, you're supposed to short out the terminals, then turn the current knob until it displays the correct value.

What I'm wondering is if I have to do this every time I want to change the current limit, or if it's just so can have an easy way to see what value I'm setting. I'd imagine if I know roughly where on the knob 1A is I can just ballpark it and turn it to that without needing to short the terminals to see the readout. Or is it designed in such a way that you have to short it to even change the limit? Seems kinda annoying.

[Anonymous No.14714466]

>tfw anime anon helped me out with my stupid questions because he's a super genius and I now have a cushy 100k per year job in the mid west
Kek.