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# /sci/ - Science & Math

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Molecular spectroscopy edition
>what is /sqt/ for
Questions regarding math and science, plus appropriate advice requests.
>where do I go for other SFW questions and requests?
>>>/wsr/ , >>>/g/sqt , >>>/diy/sqt , >>>/adv/ , etc.
>books?
https://stitz-zeager.com/
>journal articles?
>book recs?
https://4chan-science.fandom.com/wiki//sci/_Wiki
>how do I post math symbols?
>how do I successfully post math symbols?
https://imgur.com/a/pxKrrdO
>a google search didn't return anything, is there anything else I should try before asking the question here?
>where do I look up if the question has already been asked on /sci/?
>>>>/sci/
https://boards.fireden.net/sci/
>how do I optimize an image losslessly?
https://trimage.org/
https://pnggauntlet.com/

>attach an image
>make sure relevant variables are clearly defined
>if a question has two or three replies, people usually assume it's already been answered
>check the Latex with the Tex button on the posting box
>if someone replies to your question with a shitpost, ignore it

Stuff:
Meme charts: https://imgur.com/a/kAiPAJx
Serious charts: https://imgur.com/a/Bumj2FW (Post any that I've missed.)
Verbitsky: https://imgur.com/a/QgEw4XN
https://pastebin.com/SmBc26uh
Graphing: https://www.desmos.com/
Calc solver: https://www.wolframalpha.com/
Tables, properties, material selection:
https://www.engineeringtoolbox.com/
http://www.matweb.com/

 >> Anonymous Wed Sep 16 13:11:18 2020 No.12128104 File: 364 KB, 780x4182, 1600202762696.png [View same] [iqdb] [saucenao] [google] [report] last thread: >>12108436unanswered questions and their fields:>>12122742 || anatomy>>12125006 || anatomy>>12125091 || anatomy>>12111359 || anatomy/biology>>12108565 || biology>>12113957 || biochemistry>>12119726 || chemistry>>12116906 || earth science>>12117094 || electronics>>12108614 || math>>12121624 || math>>12115337 || mathematical physics>>12113648 || physics>>12128044 || physics>>12127322 || misc.
 >> Anonymous Wed Sep 16 13:15:55 2020 No.12128125 >>12128044your understanding of LEDs is pretty poor. the two different types of semiconductors, n and p types, have either an abundance or a lack of electrons (respectively). flowing a current through this causes electrons at the junction from the n-type to recombine with the p-type holes.these two are at different energy levels corresponding to the band gap, so when the electron drops in energy it emits light corresponding to that energy.
 >> Anonymous Wed Sep 16 13:29:39 2020 No.12128174 File: 70 KB, 726x179, Screenshot 2020-09-16 132731.png [View same] [iqdb] [saucenao] [google] [report] Can someone explain to me why elastic potential energy at (a) would be 0 while elastic potential energy at (b) would be max? I thought that at (a) it would be the highest potential energy and at (b) it would have the lowest elastic potential energy because it's also where the kinetic energy is at the highest.
 >> Anonymous Wed Sep 16 13:53:32 2020 No.12128242 >>12128174if you take an infinitesimal element of the string, the elastic potential will be greatest when it's being stretched the most (U=kx^2). so, we have to figure out where this maximum stretch is.since your string is not stretching at all in the x direction, any stretch has to be vertical. at the peaks of the wave, the point at the peak has no vertical stretch (slope=0). the slope at y=0 is the largest, and you can see the string is stretched the most vertically there.you're probably thinking of gravitational potential energy, which would be the highest at a since the segment of the string is the highest. either that, or you're thinking of the string as a spring with equilibrium position y=0 and maximum/minimum at ym. this is not correct, you need to think of the string as one long spring and pick the point where that spring would be stretched the most.
 >> Anonymous Wed Sep 16 13:58:32 2020 No.12128254 >>12113957oxidation>>12119726question unclear. Is there a semi-permeable membrane involved? When you say 10:1, what exactly is the 10? K+, or KCl?Is a neutral counterion like NO3- present?
 >> Anonymous Wed Sep 16 13:59:27 2020 No.12128258 >>12128174E_pot=kx^2highest displacement -> highest potential energyAlso v=0 at (a), so E_kin=0
 >> Anonymous Wed Sep 16 14:09:15 2020 No.12128291 >>12128242>you're probably thinking of gravitational potential energy, which would be the highest at a since the segment of the string is the highest.Yea I was thinking of it that way which really did confuse me.>any stretch has to be vertical. at the peaks of the wave, the point at the peak has no vertical stretch (slope=0). the slope at y=0 is the largest, and you can see the string is stretched the most vertically there.Okay yeah, I think I'm getting what you mean now. At slope = 0, the string is 'back to normal' and at the highest slope, the string is the most stretched so it has the most 'tension stretch'(like a rubberband I guess?) which builds up a lot of potential energy waiting to be released... right?>>12128258>highest displacement -> highest potential energyGot it, highest displacement in terms of amplitude (ym). Thank you both so much!
 >> Anonymous Wed Sep 16 14:23:55 2020 No.12128335 im thinking of picking up smoking, what brand do you guys rec (burgerstan)
 >> Anonymous Wed Sep 16 14:25:47 2020 No.12128339 >>12128335I recommend you talk to my grandmother who is currently on a manual breathing machine in the ICU due to COPD from smoking for just 10 years when she was younger.
 >> Anonymous Wed Sep 16 14:26:57 2020 No.12128342 >>12128339whats her number
 >> Anonymous Wed Sep 16 14:27:06 2020 No.12128343 File: 10 KB, 223x226, download (2).jpg [View same] [iqdb] [saucenao] [google] [report] >>12128335Marlboro reds.
 >> Anonymous Wed Sep 16 14:28:22 2020 No.12128347 >>12128339>Smoking badAbsolute reddit take.
 >> Anonymous Wed Sep 16 14:28:36 2020 No.12128348 >>12128342Go ahead and smoke, if you're that retarded to pick it up then you deserve the abysmal death that almost every smoker experiences
 >> Anonymous Wed Sep 16 14:29:49 2020 No.12128352 >>12128339>10 yearsi only got 2 more years of undergrad + 7 years for phd so im in the clear
 >> Anonymous Wed Sep 16 14:32:30 2020 No.12128363 >>12128348There is nothing wrong with smoking, though.
 >> Anonymous Wed Sep 16 14:41:38 2020 No.12128385 File: 36 KB, 489x627, g3tcfqpznoo41.jpg [View same] [iqdb] [saucenao] [google] [report]
 >> Anonymous Wed Sep 16 14:42:13 2020 No.12128389 File: 247 KB, 863x515, how do we know what the lower electriacl potential is.png [View same] [iqdb] [saucenao] [google] [report] How do we know what the lower electrical potential of the circuit based on the diagram 2.10? Or is there a formula for it?
 >> Anonymous Wed Sep 16 14:57:32 2020 No.12128454 >>12128385Not an argument. Smoking is linked to many positive health benefits.
 >> Anonymous Wed Sep 16 15:41:21 2020 No.12128559 File: 843 KB, 1200x1200, __kaku_seiga_touhou_drawn_by_sokura_mochichitose__081060d6de4b368ff8fca0a552a8b06c.jpg [View same] [iqdb] [saucenao] [google] [report] >>12128061>>12128104Nice job lad.By the by, warosu added >> to its own link when you got the pasta from the archive.Also, you can link to sci-hub.tw now.And feel free to modify it more, it wasn't written so it would stay the same forever.
 >> Anonymous Wed Sep 16 16:09:15 2020 No.12128644 >>12128559yeah next time I'll put more work into tweaking it. there's a lot of info, I might condense it a bit
 >> Anonymous Wed Sep 16 16:11:05 2020 No.12128651 File: 26 KB, 385x178, inequality.png [View same] [iqdb] [saucenao] [google] [report] How to use the Cauchy schwarz inequality to prove pic? I've been messing this one up for a while and think i'm just not seeing the obvious.
 >> Anonymous Wed Sep 16 16:23:15 2020 No.12128689 File: 463 KB, 1242x1501, 1577773021593.jpg [View same] [iqdb] [saucenao] [google] [report] >>12128651$\left(\sum_{j=1}^n|x_jy_j|\right)^2 \leq \sum_{j=1}^n|x_j|^2 \sum_{j=1}^n|y_j|^2$So assuming you are dealing with positive real numbers $a_j,b_j$Let [eqn]x_j = \frac{a_j}{\sqrt{b_j}}, \quad \text{ and } \quad y_j = \sqrt{b_j}[/eqn]Then you easily obtain[eqn]\left(\sum_{j=1}^n \left|\frac{a_j}{\sqrt{b_j}}\sqrt{b_j}\right|\right)^2 \ \leq \left(\sum_{j=1}^n\left|\frac{a_j}{\sqrt{b_j}}\right|^2\right)\left(\sum_{j=1}^n\sqrt{b_j}^2\right)[/eqn]From here your equation follows easily.
 >> Anonymous Wed Sep 16 16:26:22 2020 No.12128694 a cube has a diagonal of length 2 what is the side length of the cube?Exactly, no decimals
 >> Anonymous Wed Sep 16 16:29:22 2020 No.12128704 >>12128694$\frac{2}{\sqrt{3}}$
 >> Anonymous Wed Sep 16 16:39:48 2020 No.12128740 >>12128689Isn't this just plugging in something to fit? I felt like I was supposed to derive that one in the picture from cauchy-schwarz. Driving me crazy.
 >> Anonymous Wed Sep 16 16:41:37 2020 No.12128745 File: 23 KB, 458x336, AnsoffMatrix.jpg [View same] [iqdb] [saucenao] [google] [report] Is there a specific name for this type of diagram or categorization? I.e. 2 pairs of categories resulting in a category for every combination of those.
 >> Anonymous Wed Sep 16 16:44:22 2020 No.12128759 >>12128745decision matrix
 >> Anonymous Wed Sep 16 16:51:05 2020 No.12128788 >>12128759Nah, that's too specific
 >> Anonymous Wed Sep 16 16:53:43 2020 No.12128795 File: 61 KB, 1300x866, 40800869-2d-cartoon-image-of-table.jpg [View same] [iqdb] [saucenao] [google] [report] >>12128788then it's just a type of tablepic related when you google 2D table
 >> Anonymous Wed Sep 16 16:54:40 2020 No.12128796 File: 1.71 MB, 3472x3433, IMG_20200916_135149_1.jpg [View same] [iqdb] [saucenao] [google] [report] I know the limits of h and the lower limit of t but I can't figure out how to set up the integral because Im dumbpls halp
 >> Anonymous Wed Sep 16 16:56:45 2020 No.12128802 >>12128796it would be helpful if you described what the problem was so we didn't have to read your mind
 >> Anonymous Wed Sep 16 17:02:58 2020 No.12128825 >>12128796What are we even looking at?
 >> Anonymous Wed Sep 16 17:06:11 2020 No.12128833 >>12128796Like, I can read the thing.I literally just don't know what it is you want to do.>>12128825Water falls in big circle and leaves through small circle.
 >> Anonymous Wed Sep 16 17:43:01 2020 No.12128907 Is Linguistics a good major to double major with Applied Mathematics ?
 >> Anonymous Wed Sep 16 17:44:13 2020 No.12128914 >>12128907do you like linguistics? if yes, then do it.nothing makes a "good" major besides what you want to major in and what you want to do with your life.
 >> Anonymous Wed Sep 16 17:45:55 2020 No.12128921 >>12128914This but unironically.
 >> Anonymous Wed Sep 16 17:46:28 2020 No.12128925 >>12128914>>12128914But are they synergistic? I'm looking at it from a perspective of developing human-accurate speech synthesis.
 >> Anonymous Wed Sep 16 17:49:26 2020 No.12128931 >>12128921my post was unironic>>12128925if you want to do anything that involves both fields then sure. most likely your major will be 1% of your knowledge going into the field, and the remaining 99% you'll learn doing the work and learning the specifics to your field.
 >> Anonymous Wed Sep 16 17:50:34 2020 No.12128934 >>12128925I majored in math and minored in Korean, for what it's worth.
 >> Anonymous Wed Sep 16 17:55:15 2020 No.12128948 How does subtracting the starting point to the end point on a graph finds its change? I can't visualize it in my head when negative numbers are involve. Help
 >> Anonymous Wed Sep 16 17:56:41 2020 No.12128955 >>12128802>>12128825>>12128833some stuff flows into a tank at 32kg/s, density 2500kgm-3cross sectional area of tank has radius r1cross section of exit pipe has radius r2the speed it leaves is sqrt(2gh)so volume flow in = 32/2500mass out = sqrt(2gh)*(pi*r2^2)This problem starts when the height of the fluid is h1 (I know what it is) and I need to found how long it takes to overflow the tank (height of the tank is h2 = h1 + 2)
 >> Anonymous Wed Sep 16 17:59:15 2020 No.12128960 >>12128948the change of a graph is the difference of the y-values from start to finish. it's like with anything else, subtraction finds the change. if you want to lose weight, and you weigh 500 pounds and then you go to 250 pounds, your weight change is 250-500=-250 pounds.say your house is at x=0. if you walk to the right, you walk in the "positive" x direction, and to the left is the "negative" x direction. say you start at 5 meters to the left of your house and then walk to 5 meters to the right. how far did you walk? 5-(-5)=10 meters
 >> Anonymous Wed Sep 16 18:02:00 2020 No.12128965   >>12128955You know how much volume accumulates per second into the tank and you know the tank's volume, what are you messing with the height for?
 >> Anonymous Wed Sep 16 18:04:05 2020 No.12128973 Let $k \in \mathbb{N}, 0 \le c_1 < ... < c_k \le 1$$a, b \in \mathbb{R}, a < b$$b_1, ... , b_k \in \mathbb{R}$For $f: [a,b] \to \mathbb{R}$ and $h = b - a$ the quadrature rule Q is given as$Q(f) = h\sum_{n=1}^{k} b_jf(a + c_jh)$If f is integrable define the error R(f) of f as$R(f) = \int\limits_{a}^{b} f dx - Q(f)$Show, if $m \in \mathbb{N}, m \ge k - 1$ and Q is exact all polynomials with degree at most m(meaning for all polynomials q with deg(q) $\le m$ it holds that $R(q) = 0$$\exists c \in \mathbb{R}^{+}$ such that $\forall f \in C^{m+1}([a,b])$ it holds that[eqn]\vert R(f)\vert \le ch^{m+2}\|f^{(m+1)}\|_{\infty}[/eqn]with c being independent of the interval [a,b].Hint: Expand $0 \le c_1 < ... < c_k \le 1$ to $0 \le c_1 < ... < c_{m+1} \le 1$ and interpolate f with a polynom q of degree m at $a+c_1h < ... < a+c_{m+1}h \le 1$
 >> Anonymous Wed Sep 16 18:04:43 2020 No.12128978 File: 84 KB, 952x487, fknwut.png [View same] [iqdb] [saucenao] [google] [report] I have no idea what to do here. I'm feeling ultra dumb.
 >> Anonymous Wed Sep 16 18:16:40 2020 No.12129026 File: 213 KB, 600x658, __remilia_scarlet_and_flandre_scarlet_touhou_drawn_by_arnest__f472c1e784c502b9ef9f41eb730dea00.png [View same] [iqdb] [saucenao] [google] [report] >>12128978$a_1 = 1, a_2 = 4, a_3 = 9, b_1= a+b, b_2 = c, b_3 = a+b+c$
 >> Anonymous Wed Sep 16 18:18:34 2020 No.12129028 >>12129026kill me now. ty
 >> Anonymous Wed Sep 16 18:19:00 2020 No.12129030 >>12129026Based.
 >> Anonymous Wed Sep 16 18:21:02 2020 No.12129036 >>12129028>kill me nowNo, no, this is some real schizo wild guessing shit, there's really no shame in getting stuck.
 >> Anonymous Wed Sep 16 18:25:07 2020 No.12129050 >>12129036Well, I just realized that it's even easier. Take the LHS, and just plug into RHS of the other inequality. Like a_1 =1, a_2=16, a_3=81., b_1=a+b, b_2=c, b_3=a+b+c.However, still not sure about >>12128651The other anon was kind enough to answer, but it just feels ad hoc.
 >> Anonymous Wed Sep 16 18:31:48 2020 No.12129067 Given a random variable X and a borel function f such that fX is not a.s. constant, is it possible that X and fX are independent? I'm pretty sure that it is no.
 >> Anonymous Wed Sep 16 18:38:03 2020 No.12129084 >>12128960I'm confused. So say I'm "*" and "0" is my house, I start 5 meters to the left of my houseSo* - - - - 0 + + + + +Then I walk 5 meters to the rightSo- * - - - 0 + + + + + (Step 1)- - * - - 0 + + + + + (Step 2)- - - * - 0 + + + + + (Step 3)- - - - * 0 + + + + + (Step 4)- - - - - * + + + + + (Step 5)Isn't it 5 meters I walked?
 >> Anonymous Wed Sep 16 18:42:11 2020 No.12129094 >>12129050And by even easier I just mean the same thing. Oy.
 >> Anonymous Wed Sep 16 18:47:02 2020 No.12129103 >>12129084what?if you start 5 meters above water, and you dive to 5 meters below the surface of the water, how many meters down did you go?what is your notation, do you have no math experience whatsoever?
 >> Anonymous Wed Sep 16 18:52:31 2020 No.12129120 >>12129067It's obviously false, but my complete lack of skills at manipulating probability theoretic definitions makes it hard to prove.There was a definition like "random variables $X$ and $Y$ are independent if and only if for any two measurable sets $A, B \subset \mathbb{R}$, $P[ X^{-1}(A) \cap Y^{-1}(B)] = P[X^{-1}(A)]P[Y^{-1}(B)]$", wasn't there? It's pretty easy to prove it from that.
 >> Anonymous Wed Sep 16 18:58:45 2020 No.12129134 >>12128125That’s not really answering the question. You can’t recombine ad Infinitum. My question was how are LED able to continuously do this.
 >> Anonymous Wed Sep 16 19:00:23 2020 No.12129139 >>12129134yes, you can. because the electrons that go from the n to p type semiconductors are then drawn out into the circuit to form the current.for any electron that goes from n->p semiconductors, a new one is popped out of the p-type and flows into the wire of the circuit.
 >> Anonymous Wed Sep 16 19:03:20 2020 No.12129149 >>12128704How would you calc this without trig / a computer?
 >> Anonymous Wed Sep 16 19:06:25 2020 No.12129156 >>12129149I used my brainfor a square (since it's simpler than a cube to visualize) you have four sides. the diagonal is the line connecting any two opposite corners. so, you imagine a triangle formed by the two sides of the square with the diagonal as the hypoteneuse, and you calculate the side length from therefor a cube it's the same problem, but there are three side lengths that you need (since it's 3D). if you have trouble seeing this, use a physical 3D cube and imagine what the sides of the diagonal would be.
 >> Anonymous Wed Sep 16 19:09:29 2020 No.12129161 >>12128389Just define it to be ground or 0 volts.
 >> Anonymous Wed Sep 16 19:22:41 2020 No.12129198 >>12129156Did you consider that the diagonal of a cube is the diagonal of a rectangle with different a and b, where a is the side length of the cube and b is the hypotenuse of the squares? I’m just curious the method for tackling, it’s still strange to me that the diagonal of a unit square is sqrt2 but for a cube is sqrt3
 >> Anonymous Wed Sep 16 19:24:19 2020 No.12129207 >>12129103>say you start at 5 meters to the left of your house and then walk to 5 meters to the right.Ohh, so it meant I start 5 meters to the left of my house and walk 5 meters to the right from my house? I thought it meant I start 5 meters to the left of my house and then walk 5 meters to the right from 5 meters to the left.I only know pretty basic algebra and im kinda retarded
 >> Anonymous Wed Sep 16 19:25:00 2020 No.12129210 >>12129198no matter how you do it you'll get the same answerlook up how to calculate distances in 3D
 >> Anonymous Wed Sep 16 19:26:58 2020 No.12129217 >>12129207yes, that's what I meantyou need to work on familiarity with negative numbers. do these problems:>I started at x=-100 meters and ran to x=-80 meters, how many meters did I run?>It was cold today but warm yesterday! Yesterday it was 50 degrees but today it was -100 degrees. What was the change in temperature between the two days?
 >> Anonymous Wed Sep 16 19:29:52 2020 No.12129227 >>12129217Okay thank you
 >> Anonymous Wed Sep 16 19:56:10 2020 No.12129307 >>12129149https://en.wikipedia.org/wiki/Euclidean_distance#Three_dimensionsThe length of the diagonal for a cube of length $l$ is given by $\sqrt{l^2 + l^2 + l^2} = \sqrt{3l^2} = \sqrt{3}l$. If you set this expression equal to $2$, you can solve for the length.
 >> Anonymous Wed Sep 16 19:58:42 2020 No.12129316 >>12129307>for a cube of length $l$*of SIDE length $l$
 >> Anonymous Wed Sep 16 20:36:30 2020 No.12129407 >>12128061What should I read if I want to know what there was before everything? I cannot wrap my head around how the universe has started, and the answer "it has always existed" doesn't make intuitive sense to me.So any books or other resources? Btw I'm an almost graduate physics student
 >> Anonymous Wed Sep 16 20:38:31 2020 No.12129410 >>12129407if you're almost a graduate physicist you should know that this question is metaphysics. nothing in physics currently addresses this. there's not an answer
 >> Anonymous Wed Sep 16 20:49:36 2020 No.12129445
 >> Anonymous Wed Sep 16 20:52:19 2020 No.12129455 >>12129445stephen hawkings was notorious for making claims outside of his area of expertisealso, prove it. perform any sort of experiment that provides evidence for this. unfortunately, you can't
 >> Anonymous Wed Sep 16 21:12:30 2020 No.12129503 >>12129455So whose area of expertise is it? Who would be a physicist more qualified that has written something about it?>perform any sort of experiment that provides evidence for this. unfortunately, you can'tWhen you can't make experiments you can still formulate theories. There must be some book or some other resource that gathers and explains the theories that have been proposed up until now
 >> Anonymous Wed Sep 16 21:14:53 2020 No.12129515 >>12129503nobody, because everyone's ideas are equally shitthere's literally no way to formulate a pre-big bang theory because we have actually 0 idea about what things were like. we don't even have a starting point.you might as well go to >>>/x/ and ask what they have to say because it will be just as scientific as hawkings theory
 >> Anonymous Wed Sep 16 21:21:43 2020 No.12129538 File: 163 KB, 800x566, 1599214944974.jpg [View same] [iqdb] [saucenao] [google] [report] >Never manage to study>Realize the deadline is close, study with intense concentration How do I fix this? I could do so much more with my life if I had that drive every day
 >> Anonymous Wed Sep 16 21:34:50 2020 No.12129577 >>12129538you're probably doing other shit every dayremove the ability to do those things. get rid of your internet access
 >> Anonymous Wed Sep 16 21:51:26 2020 No.12129606 >>12129515>nobodyIf it is nobody's area of expertise then it is not an area of expertise at all. So your critic of hawking doesn't make sense.>everyone's ideas are equally shitOk, then there must be something where these ideas have been discussed and proven to be shit
 >> Anonymous Thu Sep 17 00:12:06 2020 No.12129984 Why does Lagrangian Mechanics use T - V instead of V - T ?It seems much more intuitive to me to imagine potential energy being subtracted by kinetic energy, because the potential energy is transferred into kinetic energy.I merely looked over it, but it seems like the integral and the average should be the same, and both should reflect the total energy of the system.
 >> Anonymous Thu Sep 17 00:13:42 2020 No.12129991 >>12129606nowhere did I claim it to be anyone's area of expertise. your initial link was about hawking, and I was claiming that he didn't know what he was talking about>discussed and proven to be shityou don't get it. no theory makes any sense. we literally cannot know about how things were before the big bang, at the moment. I highly doubt you're "nearing grad school in physics" if you ask these questions.
 >> Anonymous Thu Sep 17 02:30:44 2020 No.12130294 what is an average h index for a professor of physics? one of mine has an h index of 102 which seems high but i dont know what to compare it to. he wrote a textbook that is basically the manual for his subfield though so it might be why
 >> Anonymous Thu Sep 17 04:12:37 2020 No.12130440 Humanity builds a research facility on the Moon. What kind of research could be conducted here?
 >> Anonymous Thu Sep 17 04:43:35 2020 No.12130488 I took an IQ test a few years back and got 130. How fucked am I?
 >> Anonymous Thu Sep 17 06:13:23 2020 No.12130663 >>12128104Pls respond >>12115337 # || mathematical physics
 >> Anonymous Thu Sep 17 06:31:12 2020 No.12130689 File: 25 KB, 639x165, Capture.png [View same] [iqdb] [saucenao] [google] [report] >>12128061Could someone explain how the y^2 became (-1/y^2), I though we were substituting the x and y components straight into the equation for a separable differential equation. Why has it done this?
 >> Anonymous Thu Sep 17 06:49:58 2020 No.12130717 File: 97 KB, 1440x810, Me seething.jpg [View same] [iqdb] [saucenao] [google] [report] >>12130689Nevermind, I get it. Geeez, that's such an awkward way of getting to the dy/dx bit,
 >> Anonymous Thu Sep 17 08:07:32 2020 No.12130856 Is making>asterisk triangle program>real time stopwatch program>website page redesign >web where you can post edit and filter commentDoable under 2 hours or am i just a complete retard because i can't finish it on time?
 >> Anonymous Thu Sep 17 08:09:22 2020 No.12130857 arccos() isn't distributive, right?
 >> Anonymous Thu Sep 17 08:58:13 2020 No.12130946 >>12130857Do you mean linear?No
 >> Anonymouse Thu Sep 17 08:58:56 2020 No.12130947 >>12130857Usually I see distributivity phrased as "Binary operation A is distributive over binary operation B". What do you have in mind for the meaning of "Function f() is distributive"? It's true that arccos(x+y) is not in general equal to arccos(x) + arccos(y), if that's what you are asking.
 >> Anonymous Thu Sep 17 09:04:41 2020 No.12130958 >>12130946it is up to the first order approximation
 >> Anonymous Thu Sep 17 09:29:59 2020 No.12131005 >>12129991If you refer to something as an "area of expertise" then you imply that there are some experts in it, otherwise it's just bad wording.>you don't get it. no theory makes any senseOk>a random 4chan users tell me that any guess about the beginning of time is utter nonsense, and even trying is silly>one of the most renown scientist of the last century has at least formulated a theory about itI hope it's obvious that I wont stop my research here because of what you say. But if you have some source to discredit Hawking's theory, or to discredit in general any attempt at such theories, I may
 >> Anonymous Thu Sep 17 12:09:22 2020 No.12131610 File: 105 KB, 1080x1080, blocks.png [View same] [iqdb] [saucenao] [google] [report] >>12128061Is there any simulator for these kinds of things.... I hate these slope problems.... how do I find the weight A neccesary to keep the system in balance !??this is the best I could do but it isnt good
 >> Anonymous Thu Sep 17 12:17:53 2020 No.12131636 File: 127 KB, 900x900, autist in sqt.jpg [View same] [iqdb] [saucenao] [google] [report] >>/sci/thread/S12005353#p12038383I'm not sure if this was referring to me, but if it was, I'm listening.
 >> Anonymous Thu Sep 17 12:18:22 2020 No.12131639 Question to ee fags, how do you calculate the sop or karnaugh map for a system with more than 5 inputs with more than 10 bits total? You can't obviously do it by hand, so how do I do this? I'm trying to develop PLC code
 >> Anonymous Thu Sep 17 12:34:59 2020 No.12131698 How do I solve the PDEgyUx - gxUx = 0Where gy and gx are partial derivatives of some function g(x, y). I'm trying to solve for a U. I understand how to solveaUx-bUy=0 where a and b are constants, but not the above question with gx and gy.
 >> Anonymous Thu Sep 17 12:37:33 2020 No.12131705 >>12130294100 is very high. they must be important in the field.in physics even the big shots in my field are around 50-75. the highest one I've seen is 150, whch is almost unheard of
 >> Anonymous Thu Sep 17 12:38:48 2020 No.12131712 Any interesting questions I should ask my alumni who works at pretty big companies?
 >> Anonymous Thu Sep 17 12:38:48 2020 No.12131713 >>12130856depending on your experience and how sophisticated you want it to be. the first two seem much easier but I have never done anything like the latter two.are you talking with a full-blown GUI?
 >> Anonymous Thu Sep 17 12:41:22 2020 No.12131720 >>12131005Russel's teapot.Anyone can come up with something that works. The problem is there's no possible way of knowing which theories are better than the others because there's no proof. The big bang erased any information of a pre-existing universe.It's like asking which beyond standard model is currently true. We have no idea, we just have a lot of theories that we're currently testing. But at least we're able to test them. Unless you can devise an experiment to test pre-big bang dynamics, then any theory might as well be "there were magic unicorns that rules over everything."
 >> Anonymous Thu Sep 17 12:43:40 2020 No.12131729 >>12131712here are my go-to questions for people like thisdon't ask boring questions that you can look up btw.>is there anything you wish you knew in my position that you know now?>what aspect of your career preparation (connections, experience) would you say was most importantidk probably some others but that's a start
 >> Anonymous Thu Sep 17 12:44:43 2020 No.12131734 >>12131713The web redesign is more of the view/display without the functional, so it's being tricky on the css part. For the last one it's a web but they didn't really talk about the design so probably they want to focused on the functionality, they asked to use framework and make sure it's secured from xss attack
 >> Anonymous Thu Sep 17 12:45:28 2020 No.12131738 >>12131610by in balance, do you mean stationary?it's been a long time since I've done mechanics but I'll give it a shot.
 >> Anonymous Thu Sep 17 12:47:57 2020 No.12131743 >>12131738yes stationary
 >> Anonymous Thu Sep 17 12:54:29 2020 No.12131762 >>12131698Rewrite as $(g_y - g_x)U_x = 0$.The solutions should mostly be constant in terms of x.
 >> Anonymous Thu Sep 17 12:56:19 2020 No.12131772 >>12131762>>12131698Ah fuck I mistyped itWhat I meant to type was:gyUx - gxUy = 0
 >> Anonymous Thu Sep 17 12:56:50 2020 No.12131773 File: 21 KB, 581x192, geometry.png [View same] [iqdb] [saucenao] [google] [report] how do I find hplease don't laugh
 >> Anonymous Thu Sep 17 12:59:51 2020 No.12131782 >>12131772You just want *some* non-trivial U? Because U=g works.
 >> Anonymous Thu Sep 17 13:01:23 2020 No.12131786 >>12131782Yes exactly. I even guessed that would be the answer, I just can't figure out the actual working to get to it
 >> Anonymous Thu Sep 17 13:03:17 2020 No.12131795 >>12131786>>12131762What I mean is, is how do I work towards the solution U=g without assuming its that in the first place?
 >> Anonymous Thu Sep 17 13:04:19 2020 No.12131800 >>12131795Meant for>>12131782
 >> Anonymous Thu Sep 17 13:08:27 2020 No.12131812 >>12131773okay nobody replied yet but I got:Rtan(30) + Rtan(60) = L for the length of each black line so then the height h would be Lsin(30)any smart people wanna confirm?
 >> Anonymous Thu Sep 17 13:11:29 2020 No.12131820 >>12131786I personally solved it with inspection, but if you want a maymay justification, then sure, I can give you one.Notice that $g_y U_x - g_x U_y = \omega (\nabla U, \nabla g) = 0$, where $\omega$ is the usual euclidean symplectic form. Symplectic forms are alternating, so for bidimensional space, any vector field $X$ solving $\omega (X, \nabla g)$ has the form $X = f(x) \nabla g$ for some function $f(x)$ on the points where $g$ is non-zero. Taking $f(x) = 1$ gives our current solution.You can then try to mess around with properties of conservative vector fields and see if anything else shows up to pass the time.
 >> Anonymous Thu Sep 17 13:17:09 2020 No.12131834 >>12131743>>12131610okay two things:I just did the whole problem without realizing that A is on a string. you really really need to write out your problems better because I'm trying to interpret what you're asking based on your scratch workfrictional force is not equal to $\mu N$ , this is the MAXIMUM static frictional force that is possible. Since you have no motion, your actual frictional force will just be equal and opposite to the applied forces on your object (gravity) in order to cancel them out.if you want me to work through the problem I'll need you to actually state what the question is, sorry.
 >> Anonymous Thu Sep 17 13:17:31 2020 No.12131835 >>12131820Rather than a symplectic form, it might be easier for you to think of the determinant of [eqn]\begin{pmatrix}g_y & g_x \\U_y & U_x\end{pmatrix}[/eqn]See? only zeroes when one is a multiple of the other.
 >> Anonymous Thu Sep 17 13:18:29 2020 No.12131840 File: 48 KB, 284x652, 1597361117975.jpg [View same] [iqdb] [saucenao] [google] [report] about to take my first electromagnetics exam, thanks for all the help bros
 >> Anonymous Thu Sep 17 13:25:20 2020 No.12131848 >>12131835>>12131820I'm only just starting PDEs so a lot of this terminology I'm still learning. I came up with a reasonably decent inspect justification (I think).However I've taken a screen shot of your proof to slowly take in as I do the course, thank you very much. Which textbooks do you recommend learning PDEs from? I have access to haberman and/or Evans, but can get another simple enough. Evans seems a little beyond me currently.
 >> Anonymous Thu Sep 17 13:28:26 2020 No.12131859 >>12131639Are there no EEs here?
 >> Anonymous Thu Sep 17 13:32:03 2020 No.12131871 >>12131772[eqn]U_x g_y- U_y g_x = \begin{pmatrix}U_x\\U_y\\0\end{pmatrix}\times \begin{pmatrix}g_x\\g_y\\0\end{pmatrix}[/eqn]So basically you want the cross product to be 0, which means U and g must be orthogonal
 >> Anonymous Thu Sep 17 13:36:16 2020 No.12131882 >>12131848Honestly, my knowledge of PDEs is a weird hodge podge of Appendices on stuff like elliptic pdes and other random knowledge. I can't really recommend you anything.Evans is constantly recommended, tho, so you should probably insist on making your way through it.
 >> Anonymous Thu Sep 17 13:38:55 2020 No.12131893 >>12131610>>12131834The block B is held in place on the slope by friction and block ABlock A is tied to a unmovable wall with the rope that goes parallel to the slopeIf weight of block B is known and the friction coefficients from both sides of it, then whatis the minimal weight of block A that would make the system stable ie... in placealso find the forc in the rope
 >> Anonymous Thu Sep 17 13:44:02 2020 No.12131909 >>12131882I've read the first chapter of haberman and it's very intuitive, but that's to be expected since its main focus is applied PDEs, I'll probably dig into Evans at some point since I'd like to try my hand at postgrad
 >> Anonymous Thu Sep 17 13:46:52 2020 No.12131914 Anything good I can read about burnout? I'm in a deep pit I can't seem to get out
 >> Anonymous Thu Sep 17 13:47:11 2020 No.12131915 >>12131610Do you have to use Newtonian mechanics?
 >> Anonymous Thu Sep 17 13:49:07 2020 No.12131920 >>12131914Go for a walk. A long one. Listen to an audiobook/podcast (whatever you feel like, nothing work/study related).Always helps me both unwind and recharge. If you're daring, by yourself an ice cream on your walk
 >> Anonymous Thu Sep 17 13:53:54 2020 No.12131935 File: 3.07 MB, 776x5164, 15-36-45-1514290698220.png [View same] [iqdb] [saucenao] [google] [report] Where should I start if ive just done calc 1-3 and diff eq a few years ago but want to learn more? taking a gap year before grad school and want to build on my math
 >> Anonymous Thu Sep 17 13:56:41 2020 No.12131943 >>12131935What field?Anyway, linear/abstract algebra
 >> Anonymous Thu Sep 17 14:11:44 2020 No.12131986 >>12131935AlgebraGet Pinter's book.
 >> Anonymous Thu Sep 17 14:16:34 2020 No.12132000 >>12131935Linear algebra and PDEs
 >> Anonymous Thu Sep 17 14:32:59 2020 No.12132048 File: 145 KB, 602x798, scrap.png [View same] [iqdb] [saucenao] [google] [report] >>12131893>>12131610as always, you should check my work for yourself.
 >> Anonymous Thu Sep 17 14:40:13 2020 No.12132072 >>12132048These are the worst capital sigmas I've ever seen.
 >> Anonymous Thu Sep 17 14:40:15 2020 No.12132073 >>12128061How do we know Dedekind's construction of the reals is equivalent to Cantor's construction of the reals?
 >> Anonymous Thu Sep 17 14:41:16 2020 No.12132079 >>12132073>Dedekind's construction of the realshttps://www.youtube.com/watch?v=LSWIFXP2r14
 >> Anonymous Thu Sep 17 14:41:56 2020 No.12132080 File: 28 KB, 900x779, 1592880839504.png [View same] [iqdb] [saucenao] [google] [report] >>12131840my calculator died so i had to do all the calculations by hand
 >> Anonymous Thu Sep 17 14:54:45 2020 No.12132106 >>12132080Did you do good?
 >> Anonymous Thu Sep 17 15:01:48 2020 No.12132125 >>12132080chad handman
 >> Anonymous Thu Sep 17 15:06:59 2020 No.12132136 File: 40 KB, 647x659, 87f.jpg [View same] [iqdb] [saucenao] [google] [report]
 >> Anonymous Thu Sep 17 16:05:25 2020 No.12132284 >>12132072I realized long ago I could never draw them quickly so I settled on something that I could do fast and was still unambiguous
 >> Anonymous Thu Sep 17 16:21:02 2020 No.12132329 How did the dingos do it?
 >> Anonymous Thu Sep 17 16:21:26 2020 No.12132331 >>12132048Thanks and will do
 >> Anonymous Thu Sep 17 16:32:19 2020 No.12132364 File: 96 KB, 1280x409, 1.jpg [View same] [iqdb] [saucenao] [google] [report] >>12128061Brainlet question hereCan anyone explain me the answer? I don't get it
 >> Anonymous Thu Sep 17 16:35:47 2020 No.12132372 >>12131720>The problem is there's no possible way of knowing which theories are better than the others because there's no proof. The big bang erased any information of a pre-existing universethis is just an example:https://www.sciencealert.com/astronomers-devise-a-way-to-test-predictions-of-a-pre-big-bang-universe>Did time even exist before the Big Bang? Was there some kind of reverse Universe? Everybody is welcome to their pet theory on how our Universe came to look as it does, but only one can be a winner. To help decide which ones stay and which ones go, the researchers proposed using observable attributes that we can link with discriminating features of inflation-based models.They literally talk about how to tell which theories are better than the others
 >> Anonymous Thu Sep 17 16:41:44 2020 No.12132401 >>12132372this is equivalent to saying>the theories that are better than others are the ones that recover the current universe in the right conditionsnobody is making theories that don't do that. this is a baseline condition for any new theory. even the wackiest string theory models have to recover the observable universe or else they're immediately thrown out.when I say "no way of knowing what's better than others" I thought it was implied that this meant "out of the valid theories, there's no way to know which is better than others"
 >> Anonymous Thu Sep 17 16:52:34 2020 No.12132442 >>12132364iirc, "negative y surface" means that the fluid is acting on the surface with a normal pointing in the negative direction, same reasoning goes for the lower plate
 >> Anonymous Thu Sep 17 17:32:27 2020 No.12132620 File: 60 KB, 427x640, 5b320dd7e956b3549aa727e6d4cd196a.jpg [View same] [iqdb] [saucenao] [google] [report] Is it true that if i sleep standing up,my ears center of balance tricks my brain into having a lucid dream?
 >> Anonymous Thu Sep 17 18:23:37 2020 No.12132814 File: 879 KB, 2847x3708, 0177ad765ba3ddcdfa025452ec20c617c.jpg [View same] [iqdb] [saucenao] [google] [report] Pen and paper extends analogically a man's computational power. Through notes, sketches and registers, an individual can solve problems that he otherwise couldn't, such as the accounting of dozens of items, division of large degree polynomials, evaluation of convoluted integrals, solving differential equations, inversion of matrices, and even absolutely shitty things like multiplying big numbers.Post neuralink zoomers most likely literally won't understand what this means, and this deeply saddens me. How do I cope?
 >> Anonymous Thu Sep 17 19:09:27 2020 No.12132932 >>12132814I do all my work in ms paint I don't even use pen and paper now.
 >> Anonymous Thu Sep 17 19:27:26 2020 No.12132981 >>12132932You use Paint like you use pen and paper tho, the process is the same.
 >> Anonymous Thu Sep 17 19:48:29 2020 No.12133037 >>12132814>How do I cope?easy, neuralink is never going to work, no one is actually going to get to use it.next
 >> Anonymous Thu Sep 17 19:48:46 2020 No.12133038 >>12128061Test
 >> Anonymous Thu Sep 17 20:08:15 2020 No.12133108 >>12133038Based.
 >> Anonymous Thu Sep 17 20:09:55 2020 No.12133117 What kind of follow up can climate orbiter Akatsuki do at Venus? It's not written about much in Western media and my understanding is that it's not in its ideal science orbit.
 >> Anonymous Thu Sep 17 20:19:04 2020 No.12133139 >>12133037That's fair, thanks.Also, thanks for the offer, but I don't really have any other questions.
 >> Anonymous Thu Sep 17 20:45:59 2020 No.12133188 >>12132072also, my writing on an ipad is dogshit. it's too slippery
 >> Anonymous Thu Sep 17 21:26:45 2020 No.12133315 What are the maximal ideals of $R=k[x_1,...,x_n]$ for a non algebraically closed field $k$? A source says that there is a set theoretic bijection between the maximals over $\bar k[x_1,...,x_n]$ (which consist of the ideals $(x_1-a_1,...,x_n-a_n)$, with $a_i\in \bar k$), and the maximals in $R$, modulo the action of the automorphism group $\text{Aut}(K/k)$. Is there a more explicit description? That is, in terms of polynomial generators of the maximal ideal.
 >> Anonymous Thu Sep 17 21:49:12 2020 No.12133395 File: 15 KB, 690x147, Binomial-Distribution-Formula[1].png [View same] [iqdb] [saucenao] [google] [report] Why exactly do we have the combination formula in the binomial distribution? Intuition helps me to see it but I can't exactly reason through it. It doesn't help that I do have some troubles understanding the derivation of the combination and permutation formula. I can follow the logic of the problems but when it comes to applying the formulas I just get all messed up and don't know how to proceed.
 >> Anonymous Thu Sep 17 21:52:53 2020 No.12133402 >>12133395because there are multiple ways that you can get x successes in n trialsex: 2 and 3, s is success f is failure:s s fs f sf s sthus you need to multiply the probability of getting 2 successes in 3 trials by the number of ways that you can get that (3) to weight it properly
 >> Anonymous Thu Sep 17 21:55:49 2020 No.12133416 >>12133402>>12133395the reason we have this term is because the following term, $p^x (1-p)^{n-x}$ can be interpreted as "the probability of getting x successes followed by n-x failures." That's only one way that you can get x success. The binomial coefficient gives you the number of other possible ways that this number of successes and failures can happen
 >> Anonymous Thu Sep 17 22:10:12 2020 No.12133454 >>12133402>>12133416That was a very nice explanation anon. You're good at explaining things, I think that made it quite clear, thank you
 >> Anonymous Thu Sep 17 22:12:11 2020 No.12133462 >>12133454thank you. I'm always unsure of my teaching skills since I've never had the chance to TA and get feedback. I appreciate it.
 >> Anonymous Fri Sep 18 02:29:14 2020 No.12134220 >>12134204there are No Questions, don't complain
 >> Anonymous Fri Sep 18 02:32:16 2020 No.12134233 Does a magnetic field interfere with other magnetic fields? Like a wave specifically, is there an interference pattern associated with the magnetic fields around lets say two adjacent magnets
 >> Anonymous Fri Sep 18 04:57:11 2020 No.12134726 Based on our current physics, will it ever be possible to make computers that can send data into the past?
 >> Anonymous Fri Sep 18 05:33:26 2020 No.12134827 File: 560 KB, 2190x1513, IMG_20200918_122832.jpg [View same] [iqdb] [saucenao] [google] [report] How do i solve 53? If i simplify the upper equation i get 8y+2x=3xyBut if i put the xy=8 from the lower equation to the upper one i get an equation that is not quadratic.And if i translate the lower equation to x=8/y and put it in the upper one i get x^2=40, that doesn't make sense.Where did i go wrong here?
 >> Anonymous Fri Sep 18 05:38:32 2020 No.12134843 >>121348278/x+2/y=3xy=8 -> x=8/y8/(8/y)+2/y = y+2/y = (y^2+2)/y = 3-> y^2-3y+2=0 -> y1=1, y2=28/x+2=3 -> x=88/x+1=3 -> x=4
 >> Anonymous Fri Sep 18 06:22:51 2020 No.12134913 I have learnt statistics in my own language and now there's a thing I don't know the english name of. If we have a sample size larger than 10% of the population, we can do "ändlighetskorrektionen" with (1-n/N). The swedish name means something like the finiteness correction but that's not the english name.Do any of you recognize this and know what to call it in english?
 >> Anonymous Fri Sep 18 06:45:35 2020 No.12134946 >>12133315I really doubt there is desu.Specifically, if there was a description, I can't help but picture it as "For every element in the closure's base, associate it to its least divisor in R", except that doesn't work, but in some cases it looks like it does.For example, the ideal $\langle x - i, y + i \rangle \in \bar{Q}[x, y]$ has an exotic element $x + y$ in $\mathbb{Q}[x, y]$, but if you change to $\langle x- \sqrt{2} i, y + i$ it seems like it vanishes and the least degree term kicks upward.
 >> Anonymous Fri Sep 18 08:10:20 2020 No.12135093 File: 31 KB, 468x469, 1598903418812.png [View same] [iqdb] [saucenao] [google] [report] >>12128454and innumerable negative health problems
 >> Anonymous Fri Sep 18 08:34:56 2020 No.12135133 Can /sci/ clarify just what the heck is information theory all about (specifically the concept of entropy)? You may assume background in undergrad probability theory, measure theory, computational complexity etc. Thanks!
 >> Anonymous Fri Sep 18 09:03:36 2020 No.12135160 >>12135093genuine autism
 >> Anonymous Fri Sep 18 09:09:00 2020 No.12135174 >>12134913It's Bessel's correction, named after Friedrich Bessel.
 >> Anonymous Fri Sep 18 09:16:06 2020 No.12135185 File: 819 KB, 993x699, sgz.png [View same] [iqdb] [saucenao] [google] [report] >>12135152>Don't (you) me. There is nothing you can do to argue against this. If you think you have a valid argument, shut the fuck up, go and read the evidence and then maybe, just maybe I'll consider reading your reply.>Also, for anyone who says smoking keeps them stimulated to do their job etc., think about how cucked you are that you're working for 'the man' and he's pushing you to perform beyond your body's natural capabilities that you need an artificial stimulant to keep you going (yes I know coffee counts as one too, fuck all stimulant-requiring jobs).I wish you could read this in five years and hang yourself on the fragrant bouquet of shame. The first notes resemble a large co-mingling of cringe and self-righteousness packaged in a family friendly commie anti-smoking message. The under notes are reminiscent of puritan brand vitriol and certainty of purpose, a pleasant effervescence, could it be believing this actually matters and that you aren't a paid shill?No, it is something different. There is a stinging malingering putrid acceptance of some sort of dogma. While a drug pusher is making money, a pawn is merely cast from the board. What is the game, and who benefits? Is this the salt of youth?
 >> Anonymous Fri Sep 18 09:17:05 2020 No.12135187 >>12128335>2020>smokingjust dont, if you really want to get nicotine into your body smoking is literally worst way to do it
 >> Anonymous Fri Sep 18 09:26:50 2020 No.12135210 File: 21 KB, 760x200, Screenshot_20200918-092627.png [View same] [iqdb] [saucenao] [google] [report] What's up with the colon-equals operator here?
 >> Anonymous Fri Sep 18 10:22:51 2020 No.12135376 >>12135210definition
 >> Anonymous Fri Sep 18 11:22:30 2020 No.12135575 >>12135376Right, but why not use the equals sign? I've been through spivak, apostol, and Riley+Hobson+Bence and I've never seen it used, just the equals sign.
 >> Anonymous Fri Sep 18 11:41:07 2020 No.12135631 So I know how to get the answer intuitively using the unit circle but is there any other way to get the answer? It's bothering for no good reason. I know arccos(-1/2) = 2pi/3 but how would I get 4pi/3 in a similar algebraic manner?
 >> Anonymous Fri Sep 18 11:43:32 2020 No.12135639 File: 12 KB, 539x266, 2020-09-18 11_36_16-Window.png [View same] [iqdb] [saucenao] [google] [report] >>12135631Forgot pic
 >> Anonymous Fri Sep 18 11:45:23 2020 No.12135648 >>12135631>>12135639do you know any calculus? the easiest way is to find the zeros of the first derivative of f(x)
 >> Anonymous Fri Sep 18 11:46:39 2020 No.12135654 >>12135639Cosine is symmetric around any multiple of $2 \pi$]
 >> Anonymous Fri Sep 18 11:47:45 2020 No.12135660 File: 2 KB, 141x67, matrix.png [View same] [iqdb] [saucenao] [google] [report] the expression on the left is a matrix, right? given values, how do I interpret/check if it equals zero? Do I multiply or add in some pattern? I thought it could only equal zero if all the values are zero, otherwise it can't be concatenated in a standard way to a single number without an algorithm or operations.
 >> Anonymous Fri Sep 18 11:48:37 2020 No.12135665 File: 206 KB, 500x516, 1594552927004.png [View same] [iqdb] [saucenao] [google] [report] Vent on me about your /sci/ frustrations
 >> Anonymous Fri Sep 18 11:49:06 2020 No.12135669 >>12135654*Any multiple of $\pi$ sorry
 >> Anonymous Fri Sep 18 11:49:59 2020 No.12135671 File: 322 KB, 460x690, Houjou.png [View same] [iqdb] [saucenao] [google] [report]
 >> Anonymous Fri Sep 18 11:50:46 2020 No.12135675 >>12135665My school is closed for the entire next week due to chink flu and it's driving me insane.
 >> Anonymous Fri Sep 18 11:52:13 2020 No.12135685 >>12135675what were you working on?
 >> Anonymous Fri Sep 18 11:53:16 2020 No.12135687 >>12135685CompSci.It was already dogshit to work an entire semester at home last year and it looks like it's not going to be any different this time around.
 >> Anonymous Fri Sep 18 11:53:19 2020 No.12135688 File: 307 KB, 2048x1937, __cirno_touhou_drawn_by_akiyoku__19cc4c64dd70016ff62a333f43d4d999.jpg [View same] [iqdb] [saucenao] [google] [report] >>12134204Coincidentally, people have been asking lots of stupid shit in /mg/ lately.Wanna run a psyop where we pretend to be /mg/ oldfags and tell people there to fuck off to /sqt/?>>12135575Because autism.>>12135665I'm psychologically incapable of solving literally anything that comes out of the IMO or the Putnam.
 >> Anonymous Fri Sep 18 11:56:03 2020 No.12135701 >>12135687Why do you dislike working from home?>>12135688Have you tried any of the autistic studying methods like study groups?
 >> Anonymous Fri Sep 18 11:58:50 2020 No.12135714 I got all A grades in my freshman year and I will say that at least 50% of that comes from /sqt/ helping and explaining things. I ask stuff here because I don't feel judged, or more accurately, I don't care about feeling judged by anonymous people on a cartoon forum when asking dumb questions.
 >> Anonymous Fri Sep 18 11:59:08 2020 No.12135715 >>12135665dropped not one but two classes in order to teach this lab, down to 11 hours now and feeling like a chump. i was set to graduate at 22 y/o but now its uncertain. i did it to get close with the prof and hopefully get research experience (which fortunately it seems like he likes me) but its hard making decisions without knowing their outcome, its not like theres anyone to teach you this stuff, you just have to guess and check but instead of a 2nd grade math test its my future :)
 >> Anonymous Fri Sep 18 11:59:46 2020 No.12135718 >>12135701>Why do you dislike working from home?Might be an autism thing but I feel far more compelled to pay attention and get involved when I'm physically participating in classes than in Zoom conferences.
 >> Anonymous Fri Sep 18 12:04:00 2020 No.12135739 >>12135715I honestly believe talking to the correct people is way more important than graduating or having some A or diploma or whatever I would indeed recomend getting close to academics and workers with experience >>12135718Well, just a few share of people are actually accomodated to the model of listening and copying like most schools do. Most people just has workarounds to get passing grades despite the monotony try looking up studying methods
 >> Anonymous Fri Sep 18 12:04:10 2020 No.12135740 File: 80 KB, 800x473, 1594693474454.jpg [View same] [iqdb] [saucenao] [google] [report] >>12135701>Have you tried any of the autistic studying methods like study groups?Thanks for the advice, but I don't actually care enough to do more than whining.>>12135718I'm like that too, so it's probably an autism thing.
 >> Anonymous Fri Sep 18 12:05:44 2020 No.12135748 File: 191 KB, 1000x1002, 1592973075827.png [View same] [iqdb] [saucenao] [google] [report] >>12135740care, or else
 >> Anonymous Fri Sep 18 12:08:08 2020 No.12135763 File: 211 KB, 602x535, delete this.png [View same] [iqdb] [saucenao] [google] [report] >>12135748Or else what?
 >> Anonymous Fri Sep 18 14:03:20 2020 No.12136101 File: 531 B, 32x22, Screenshot_20200918_140214.png [View same] [iqdb] [saucenao] [google] [report] >>12128061does anyone know what this symbol in discrete logic?
 >> Anonymous Fri Sep 18 14:04:30 2020 No.12136107 >>12136101i am talking about the star thing never seen it before and Wikipedia doesn't seem to have ithttps://en.wikipedia.org/wiki/List_of_logic_symbols
 >> Anonymous Fri Sep 18 15:08:05 2020 No.12136345 >>12135660As has been mentioned, it's a determinant. It will be equal to zero if the three 2D points (x0,y0), (x0',y0') and (x1,y1) are colinear.FWIW, it expands tox0'y1 - x1y0' - x0y1 + x1y0 + x0y0' - x0'y0 = 0
 >> Anonymous Fri Sep 18 15:41:52 2020 No.12136447 >>12135665I can't go into lab and my project is fucking shit. I love my lab and find the work super interesting and I know my project has to be done in order for the experiment to work, but fuck it's so dry. It's not going to lead to any publication, it's just necessary.Meanwhile I'm watching all my peers who joined at the same time start to push out papers. Shit really sucks.
 >> Anonymous Fri Sep 18 17:43:43 2020 No.12136903 Are most steps in the lithographic process for CMOS fabrication a repeat of:>lay down some material>apply photoresist>apply mask + UV>shadowed or unshadowed regions are dissolved depending on negative or positive photoresist>etch exposed regions>remove remaining photoresistWith some possible steps in between like CVD deposition of oxide? My professor sucks at explaining shit and the book is kind of vague about steps after the STI/well implantation.Also, initially is the silicon wafer completely doped to be either p/n type (depending on whether the desired substrate is p/n type) or are some regions left as raw silicon?
 >> Anonymous Fri Sep 18 17:50:45 2020 No.12136928 >>12135133It has no rigorous definition as it isn’t math and so has no axioms or formal structure and isn’t physics so it doesn’t describe the natural world. This post will have retarded seething nigger cope replies but i’m correct and always will be. >>12135575Read more math, stop being a retarded faggot. It’s used constantly to define objects. >>12135665I haven’t read any papers I’m interested in for over 2 months, have no idea what I want to work on and probably am a bit of a push over when it comes to my interests. I also hate anime posters like you.
 >> Anonymous Fri Sep 18 17:55:01 2020 No.12136948 >>12131859>Are there no EEs here?Anime posting anon on here knows every subject there is to know, so if he is around he will answer. He's one of the legitimate smart and knowledgeable people on /sci/.
 >> Anonymous Fri Sep 18 17:58:16 2020 No.12136962 File: 69 KB, 600x555, 2d2887a5c1e04b57ec52eab5c7718f2e6.jpg [View same] [iqdb] [saucenao] [google] [report] >>12136948I don't know literally anything about electrical engineering.
 >> Anonymous Fri Sep 18 18:02:50 2020 No.12136979 >>12136962You literally do.
 >> Anonymous Fri Sep 18 18:08:19 2020 No.12137005 >>12135133It's been a couple hours and no one has given a serious answer, so I'll try my hand at it:I tell you that a random variable has assumed a certain value. Say, that a dice fell on six. This is information.We want to quantitatively measure the information given by saying that an event happened. This function, $I$, naturally only depends on the probability of the event happening, so we can write it as $I(p)$. Also, if I tell you that an event of probability $p$ and an independent event of probability $q$ has also happened, the information I've told you is naturally the sum of the two individual pieces of info, and also the information associated to an event of probability $pq$ happening, and this nets us $I(pq) = I(p) + I(q)$.Because probabilities are always positive numbers smaller than one, we're led to consider $I(p) = \log _2 \frac{1}{p} = - \log _2 p$.Entropy measures, on average, how much information an event gives you, and is associated to a random variable.Most of this knowledge comes from me reading Information Theory for Electric Engineers this morning.
 >> Anonymous Fri Sep 18 18:10:10 2020 No.12137009 File: 217 KB, 880x900, thinkingkon.png [View same] [iqdb] [saucenao] [google] [report] I work as a software engineer. Making really good money. I very much could continue at my current pace and retire comfortably at 45/50. I'm on track to senior and I foresee my income increasing year over year. I work mainly with distributed systems - mostly building components & producing designs to solve scaling problems. I feel that I have stagnated - most of my days are spent doing difficult yet menial work. I have a dream. It's to become an academic & produce research. A /sci/ientist. Both my parents are PhDs and it feels wrong that I stopped at my bachelor's degree. Another reason I want to become an academic is because I am genuinely interested in some things, such as the study of complexity, graph theory, & distributed consensus. However, my golden handcuffs prevent me from doing so. I have a few questions- Do people successfully become academics in their 40s? I can become financially independent by then, but as I understand it intelligence drops off and I'm worried my age will prevent me from contributing anything meaningful- Do you guys know of people who find research opportunities as engineers, and branch out from there?- Is it possible to do high tier personal projects, get published in journals as an independent? I could produce projects and publish it under my own name. Would that be enough to work for a research wing of a company?
 >> Anonymous Fri Sep 18 18:19:27 2020 No.12137047 >>12131639>how do you calculate the sop or karnaugh map for a system with more than 5 inputs with more than 10 bits totalKarnaugh maps are useful only for few inputs to do some quick minimizations by hand. For more inputs there are better methods like Quine–McCluskey algorithm. But even they have a limited use because this is a NP-complete problem.
 >> Anonymous Fri Sep 18 18:52:07 2020 No.12137129 I was trying to look for a proof of splitting fields of separable polynomials being Galois extensions, and came across this question https://math.stackexchange.com/questions/1662557/if-e-is-the-splitting-field-for-an-irreducible-separable-polynomial-over-f-t?rq=1For the most part it makes sense to me, but there's this part that says:Let $p_{i} (x) \in F_{i} [x]$ be the minimal polynomial of $a_{i}$ over $F_{i}$. Since $p_{i} \text{ and } p$ both have $a_{i+1}$ as a root, we have $p_{i} | p$ and therefore $p_{i} \text{ has } d_{i}$ distinct roots in EAnd I have no fucking clue about where most of this even comes from, so my questions are:Why do $p_{i} \text{ and } p$ have the root $a_{i+1}$ in common?How does having one root in common imply that $p_{i}|p$?Wouldn't $p_{i}$ having $d_{i}$ distinct elements in E only hold true if $a_{i+1}$ was a primitive element?For the first question I honestly just think that the guy messed up in his statement and meant to say "Let $p_{i} (x) \in F_{i} [x]$ be the minimal polynomial of $a_{i+1}$ over $F_{i}$", because from the way he defines $F_{i}$ I'd imagine the minimal polynomial of $a_{i}$ would just be $x-a_{i}$, but maybe I'm just stupid and don't understandAnd the second question I guess makes sense because p is irreducible over F, but I don't know how to write it down more formally
 >> Anonymous Fri Sep 18 19:23:15 2020 No.12137222 If I'm given a probability mass function of $f(x) = \frac{x}{15}$ for $x = 1 , 2 , 3 , 4 , 5$, is the cumulative distribution of $X$ just given by $\int _{1} ^{+ \infty} f(x) dx$?
 >> Anonymous Fri Sep 18 19:30:22 2020 No.12137245 >>12137222Youre given a pmf and X is a discrete random random variable. The cumulative distribution function is the summation of all values before the given x value. Don't integrate because the integral is zero. If you have a continuous random variable, that integral is wrong because it will always give a fixed number. The cumulative distribution function is a function, so it needs to vary with x, and the variable is the upper bound of integration.$F_X(x) = \sum_{n\leq x} f(x).$
 >> Anonymous Fri Sep 18 19:32:40 2020 No.12137250 >>12137245Thank you.
 >> Anonymous Fri Sep 18 20:08:24 2020 No.12137382 >>12137129>Why do p_i and p have the root a_i+1 in common?They don't, actually. The minimal polynomial of $a_i$ over $F_i$ is just $(x - a_i)$, you're entirely correct.>How does having one root in common imply that pi|p?Minimal polynomial's defining property.>Wouldn't pi having di distinct elements in E only hold true if a_i+1 was a primitive element?I don't follow.
 >> Anonymous Fri Sep 18 20:25:07 2020 No.12137434 >>12137382Oh okay so if what I mentioned about the guy messing up and meaning to write that $p_{i}$ is the minimal polynomial of $a_{i+1}$ instead is correct (as opposed to $a_{i}$ which just has a linear minimal polynomial), then I can see the second part being true, I completely forgot about checking the definition with that case>I don't follow.I mean, as far as I understand (for finite extensions at least), $d_{i} = [ F_{i+1} : F_{i} ]$ implies that the minimal polynomial of a primitive element of the extension is of degree $d_{i}$ (and thus has that amount of roots). From the definition of $F_{i+1}$, I think we could just write it as $F_{i} (a_{i+1} )$ and turn it into a simple extension of $F_{i}$ so that still holds, I guess I was confused because I didn't understand why $a_{i+1}$ was a root of $p_{i}$ to begin with so the rest just didn't make much sense to me
 >> Anonymous Fri Sep 18 21:02:26 2020 No.12137532 File: 192 KB, 600x641, d2d8d788a16d063a0ef78f66260b05da1.jpg [View same] [iqdb] [saucenao] [google] [report] >>>/pol/278127415>even Tooker is in the RBG stickyLMAO.
 >> 29 Fri Sep 18 23:09:24 2020 No.12137784 I have an IQ of 139 but have been out of school for 10 years and never progressed past algebra. I'm going to need to brush up on my academics because my memory of some things has faded. Will I be able to make it through Aerospace Engineering? I've sort of formulated a plan to start in a Junior College in order to learn Trig, Precalc and Calc and such prerequisites. Afterwards I plan on transferring to a university with a competitive Aerospace Engineering program. Is my goal achievable or am I going to screw myself?
 >> Anonymous Fri Sep 18 23:12:45 2020 No.12137788 >>12137784>I have an IQ of 139Stopped reading here.
 >> Anonymous Sat Sep 19 01:07:41 2020 No.12137943 I know I've already asked if I should double major in Applied Math and Linguistics in one of these threads before but I want to ask: What are the best fields where having a degree in applied math and a degree in linguistics is advantageous? I asked in /mg/ and the answer seems to be in natural language processing, and I'm also interested in speech synthesis. The issue is that I'm kind of apprehensive about AI and AI-adjacent fields because I'm worried about the unethical uses of it (such as how you might need to farm data in order to produce sample data for speech synthesis, for example).
 >> Anonymous Sat Sep 19 02:16:28 2020 No.12138022 Do TAs usually help with homework problems? ive never had to go to office hours for previous courses but one of them is brutal now and i have no idea what to do so i will probably go to his office hours
 >> Anonymous Sat Sep 19 02:24:49 2020 No.12138040 >>12138022If they have office hours, then they'll help you with homework or any questions relating to the class. That's why they're there.
 >> Anonymous Sat Sep 19 05:19:44 2020 No.12138345 How do scientists know what journal to submit their paper to? For every subfield there are half a dozen or more journals, and usually you can't submit your findings to more than one journal at a time. Do they just go "Okay, this is the highest IF journal that will give me a chance"?
 >> Anonymous Sat Sep 19 06:45:22 2020 No.12138481 >>12137005Cheers anon, that was short and to the point.
 >> Anonymous Sat Sep 19 07:27:22 2020 No.12138526 x^2-2x=0has three solutions:201-iwolframalpha only gives 2 answers with the simple input of z^2-2z=0how do you command WA to show the 1-i ?
 >> Anonymous Sat Sep 19 08:47:53 2020 No.12138642 >>12138526nvm, im an idiot
 >> Anonymous Sat Sep 19 09:50:11 2020 No.12138790 What's a good physics text to go through while learning calculus? Just little more than a month into calc 1.
 >> Anonymous Sat Sep 19 09:59:58 2020 No.12138820 Can someone recommend a book on physics with a gentle treatment of tensors? (None of that abstract stuff). Just need some examples and use cases on the undergrad level, as basic as possible.
 >> Anonymous Sat Sep 19 10:16:03 2020 No.12138854 >>>/wsr/891507
 >> Anonymous Sat Sep 19 13:37:47 2020 No.12139315 >>12137943bump
 >> Anonymous Sat Sep 19 13:38:33 2020 No.12139319 File: 3 KB, 933x399, moment.png [View same] [iqdb] [saucenao] [google] [report] Given the moment of the rectangle about point B, is it possible to find the moment of the rectangle about point A?
 >> Anonymous Sat Sep 19 15:08:54 2020 No.12139553 >>12139319No. Consider a simpler case: a point mass m at a distance r from B; I=m*r^2. Halving r but increasing m fourfold leaves the moment of inertia about B unchanged, but the moment of inertia about some point far from B would increase roughly fourfold.
 >> Anonymous Sat Sep 19 15:44:48 2020 No.12139640 File: 185 KB, 341x320, Oscillating_pendulum.gif [View same] [iqdb] [saucenao] [google] [report] redpill me on pendulums
 >> Anonymous Sat Sep 19 16:06:31 2020 No.12139698 >>12139640What do you want to know
 >> Anonymous Sat Sep 19 16:30:30 2020 No.12139789 File: 13 KB, 629x157, snipsnap.png [View same] [iqdb] [saucenao] [google] [report] Requesting a slick, satisfying proof of this.Example of non-slick, dissatisfying proof:$\text{There is an } x' \text{ and a } y' \text{ such that } x' \neq y' \text{ and } K(x', y') \neq 0. \\ \text{Then we can take a bump function } f \text{ centered on } y' \text{ such that } f(x') = 0. \\ \text{If necessary, we can pass to } g(x) = f(y' + \epsilon (x - y')) \text{ for large epsilon to guarantee that the integral doesn't zero, q.e.d.}$
 >> Anonymous Sat Sep 19 16:42:58 2020 No.12139830 File: 73 KB, 1272x532, 1.png [View same] [iqdb] [saucenao] [google] [report] How would I go about calculating $V(N_p|\tilde{N_p})$? I know by definition that $V(Y|X)=\sum (y-E(Y|X)^2\times P(Y|X)$. So should I simply calculate $(1-[p+(1-p)(1+\tilde{N_p})])^2\times p + (1 + \tilde{N_p}-[p+(1-p)(1+\tilde{N_p})])^2\times (1-p)$?
 >> Anonymous Sat Sep 19 17:35:00 2020 No.12139966 >>12139640When dealing with chaotic systems, small angle approximation doesn't work anymore.Is that redpilled enough?
 >> Anonymous Sat Sep 19 17:37:48 2020 No.12139976 >>12136948Whatever happened to Yukarifag? God I miss that faggot...
 >> Anonymous Sat Sep 19 17:45:15 2020 No.12139997 What's the name of the paradox with the turtle?
 >> Anonymous Sat Sep 19 17:46:28 2020 No.12140004 >>12139997achilles and the tortoise?
 >> Anonymous Sat Sep 19 17:47:28 2020 No.12140008 File: 47 KB, 672x505, unknown-79.png [View same] [iqdb] [saucenao] [google] [report] can someone please tell me how they got delta A of k and f(xk, yk)? I've spent an hour on this and my head hurts
 >> Anonymous Sat Sep 19 18:25:25 2020 No.12140109 >>12139997Zeno's paradox
 >> Anonymous Sat Sep 19 18:34:02 2020 No.12140130 >>12139976They bullied him off the board, this used to happen to anyone annoying on any board before the reddit colonization.
 >> Anonymous Sat Sep 19 18:39:47 2020 No.12140140 File: 355 KB, 864x770, __hata_no_kokoro_touhou_drawn_by_rakkidei__ac85f263f3bc5a3064c0317a71133ace.jpg [View same] [iqdb] [saucenao] [google] [report] >>12139976Conjecture one:He got bored and fucked off.Conjecture two:Whenever he thinks about /sqt/ he recalls this >>/sci/thread/S11475807#p11484606 or a similar event and, because he later understood why he was wrong on an absolutely basic level, feels literally too embarassed to show his face here.Yukarifag, if you're reading this, I forgive you, everyone forgives you, come home. I post as much if not more retarded shit than you, I just eventually learned not to attach 2hus when I'm not at least 95% confident on what I'm saying.
 >> Anonymous Sat Sep 19 19:39:21 2020 No.12140249 What causes seasonl depression and is there any way to mitigate it? I just realized that today I've just been depressed a lot more than usual... Kinda just want to sleep forever despite having a bunch of tasks to do!
 >> Anonymous Sat Sep 19 20:09:35 2020 No.12140324 >>12140140Who was in the wrong here?
 >> Anonymous Sat Sep 19 20:29:57 2020 No.12140371 >>12140140so why do you people willingly deanonymize yourself on an anonymous board! why do you this to yourself? you can just earn points on stackoverflow or physicsforums or reddit. and maybe you do. but the whole point of 4chan is a stress free interaction and you should be able to post retarded shit without feeling any remorse and thats what anonymity gives you which you choose to reject!
 >> Anonymous Sat Sep 19 20:33:24 2020 No.12140383 >>12140371Because they get used to generally being correct and helpful about things, and they take the avatar to be a signal of their authority.It's pretty sad. He literally said it in the post, that he uses a 2hu when he's confident in his answer.
 >> Anonymous Sat Sep 19 20:34:26 2020 No.12140385 >>12140249>what causes seasonal depressionbeing sad>how do i mitigate itbe happy instead
 >> Anonymous Sat Sep 19 20:41:24 2020 No.12140401 >>12140371the need for social validation is more fundamental than the instinct towards higher reason. even autistic homosexual geometers cannot resist
 >> Anonymous Sat Sep 19 20:43:30 2020 No.12140407 File: 889 KB, 2321x3583, 143ea0cc6fe8ce7fded1eff2c256123a3.jpg [View same] [iqdb] [saucenao] [google] [report] >>12140324This >>/sci/thread/S11475807#p11484595 guy was either wrong for using "vector space" to refer to "topological vector space" or he was just plain wrong.>inb4 dude it's implicit when he mentioned metrizability that he means topological vector spacesNo, because, get this:He said before hand that not every vector space is a Banach space. And that's literally correct as is, see http://user.math.uzh.ch/halbeisen/publications/pdf/hamel.pdf , Lemma 3.4. Even without a topology there are completely algebraic obstructions to Banach space structures, and a space like the real vector space with countable base admits no Banach space structure.Also, topological vector spaces weren't even relevant to the discussion, what the fuck dude.I don't understand a single post Yukarifag made, but, even in hindsight months later, they still read like nonsense.Thus, I was right, everyone else was wrong, q.e.d.>>12140371I post Remilia because she's extremely cute.I post other 2hus so Remilia mixes in.If you don't want me to be recognizable, feel free to post as many Remimis as you want and pretend to be me. You can grab some here: https://safebooru.donmai.us/posts?tags=remilia_scarlet+
 >> Anonymous Sat Sep 19 21:10:16 2020 No.12140479 File: 906 KB, 1500x1400, Patchouli Knowledge reading Riemannian geometry.png [View same] [iqdb] [saucenao] [google] [report] >>12140407Thoughts on Patchouli Knowledge?
 >> Anonymous Sat Sep 19 21:20:34 2020 No.12140519 >>12140407Keep posting remilia bro, I love her and I love you
 >> Anonymous Sat Sep 19 21:31:32 2020 No.12140557 File: 12 KB, 636x44, Screen Shot 2020-09-19 at 8.30.40 PM.png [View same] [iqdb] [saucenao] [google] [report] If we take $f = 0$, that means there is no movement in either the positive or negative x direction, right?
 >> Anonymous Sat Sep 19 21:32:47 2020 No.12140561 >>12140557bro we have literally no idea what you're talking aboutI'm trying to understand this question and the best I can do is that it's some sort of mass on an inclined plane? you need to explain it better
 >> Anonymous Sat Sep 19 21:37:55 2020 No.12140573 >>12140561I'm assuming f is the frictional force so the inclined plane assumption is probably corect.
 >> Anonymous Sat Sep 19 21:39:17 2020 No.12140576 File: 37 KB, 532x232, Screen Shot 2020-09-19 at 8.36.38 PM.png [View same] [iqdb] [saucenao] [google] [report] >>12140561Sorry, basically we have the system of pic related and the forces for the x direction (positive is left; negative is right) is $m_1 g + f - Mg sin (\alpha) = 0$ and the y direction (positive is up; negative is down) is $N - Mg cos(\alpha) = 0$.I'm interested in the case where f = 0.
 >> Anonymous Sat Sep 19 21:45:47 2020 No.12140596 >>12140576f=0 just means the frictional force is 0. that means there's no coefficient of friction between the block M and the plane, or the force from the hanging mass m is exactly enough to cancel gravity in such a way that there's no friction for that reasonwhen you set up the equation $mg+f-Mg \text{sin} \alpha=0$ you're claiming that there is no x force and thus no x acceleration. setting f=0 doesn't impact this, you can have f !=0 and it would still not be accelerating in the x direction because the total x forces are 0.also, don't forget that 0 force doesn't mean 0 movement, it means 0 acceleration. if your system is starting at rest it will not move, but if it starts off moving then it will be moving in the x direction, just not accelerating.
 >> Anonymous Sat Sep 19 21:50:18 2020 No.12140611 >>12140596That makes sense. Thanks.
 >> Anonymous Sat Sep 19 22:14:02 2020 No.12140696 Is the tangent vector of a function in 3d the same as its velocity vector? So if they ask me for the tangent vector, I just differentiate the position vector?
 >> Anonymous Sat Sep 19 22:23:10 2020 No.12140716 >>12140696If you're given a position vector $\overrightarrow{p} (t)$, then the tangent vector at $t_0$ is $\overrightarrow{p'}(t_0) = \overrightarrow{v}(t_0)$.
 >> Anonymous Sat Sep 19 22:24:48 2020 No.12140721 File: 206 KB, 801x600, Higurashi.no.Naku.Koro.ni.full.179959.jpg [View same] [iqdb] [saucenao] [google] [report] im pretty sure im the only one here that posts satoko so if you see a post with satoko you know its me c:
 >> Anonymous Sat Sep 19 22:26:17 2020 No.12140728 >>12140721avatarfagging is against the global rules.
 >> Anonymous Sat Sep 19 22:27:54 2020 No.12140733 >>12140728lol
 >> Anonymous Sat Sep 19 22:29:49 2020 No.12140738 >>12140728If only.
 >> Anonymous Sat Sep 19 22:54:35 2020 No.12140801 >>12140407>If you don't want me to be recognizableWhere did I say that?? Thats not what I asked at all. I actually like to know that it is you. I love it. I asked how YOU feel about that. My point is it may feel pretty stressful to be recognizable on an otherwise anonymous board. But if you like it that people like it that you are recognizable, then it makes sense.
 >> Anonymous Sat Sep 19 23:00:19 2020 No.12140814 >>12140733>>12140801it is explicitly prohibited per the global rules.
 >> Anonymous Sat Sep 19 23:01:23 2020 No.12140816 >>12140814so are half the threads on this godforsaken board. does that mean anything?
 >> Anonymous Sat Sep 19 23:07:00 2020 No.12140828 >>12140814do you, personally, have some sort of issue against the images posted in this thread? why dont you just speak your mind like a man? because bringing up the rules makes you look like a tool
 >> Anonymous Sat Sep 19 23:37:15 2020 No.12140911 >>12128061So I'm back at school and taking calc 2, but I ran into a problem I've had trouble solving.Prove that $\frac{1}{4} \int f(x) dx = \int \frac{1}{2}f(2x)dx$Is that just because you can u-sub into$\frac{1}{4} \int f(u) du$?can I just treat $\int f(u)du$ as $\int f(x)dx$?They come out to the same answer in a definite integral because you need to replace the bounds of integration. So can I assume that they are equal in an indefinite? Logically I just think of it as the same thing written differently in this case. But my intuition probably isn't very good.
 >> Anonymous Sun Sep 20 00:49:44 2020 No.12141092 >>12140911i think you may have copied the problem down incorrectly
 >> Anonymous Sun Sep 20 00:58:37 2020 No.12141109 File: 5 KB, 416x63, pic.png [View same] [iqdb] [saucenao] [google] [report]
 >> Anonymous Sun Sep 20 01:15:30 2020 No.12141159 >>12141109yep just sub u = 2xyou can then replace f(u)du with f(x)dx
 >> Anonymous Sun Sep 20 01:35:25 2020 No.12141214 File: 617 KB, 590x393, file.png [View same] [iqdb] [saucenao] [google] [report] How do ants solve the trolley problem?
 >> Anonymous Sun Sep 20 01:40:22 2020 No.12141223 File: 79 KB, 600x422, FpJvg.jpg [View same] [iqdb] [saucenao] [google] [report] What is it called when you're trying to prove something that's not a theorem? Like something along this format but you have to prove if the conjecture is true or false? (basically what word to replace Theorem with).
 >> Anonymous Sun Sep 20 01:50:12 2020 No.12141246 >>12141223Lemma?
 >> Anonymous Sun Sep 20 01:51:32 2020 No.12141252 >>12140828I hate avatar fags, if there is a means to harm them or dissuade them from posting I'm more than happy to make use of it. Destroying one's enemies by any and all means is masculine, is the very essence of warfare. You are a faggot and a coward and I would love to watch you die in agony.>>12140816They should be permabanned from breaking global rules repeatedly and encouraging others to do the same. This is an anonymous image board for discussing the on-topic interests of the specific boards the user finds themselves on. Bringing personal identity into the fore is disrespecting the core mandates of the site. They are worse than spammers and political warriors, they are threatening anonymity and should be punished severely, bullied incessantly, driven from the site.
 >> Anonymous Sun Sep 20 01:52:37 2020 No.12141254 >>12141159thank you fren
 >> Anonymous Sun Sep 20 01:56:04 2020 No.12141257 >>12141223Theorem: Conjecture is true/Conjecture is false.Proof: The proof goes here.
 >> Anonymous Sun Sep 20 02:03:22 2020 No.12141276 >>12141252It's not that big of a deal, bro.
 >> Anonymous Sun Sep 20 09:05:17 2020 No.12142051 >>12140479Patcho is cute.>>12140721Note taken.>>12140801I don't, I'd sooner everyone drown this place in Remimis so I mix in.However, I'm willing to accept being recognized for the greater good.
 >> Anonymous Sun Sep 20 10:14:28 2020 No.12142181 >>12142051>I'd sooner everyone drown this place in Remimis so I mix in.This is the most horrible thing that could ever happen to someone who cares about their reputation. I didn't want to mention that but since you brought it up, some prankster can start posting dumb shit from your name. It is equivalent to being hacked. You don't want that. We should really stop talking about this. I only wish you the best and I don't want to give anyone any ideas. This place is full of idiots and with posters like you or that other anime poster gone, it will be just IQ and /pol/ threads.
 >> Anonymous Sun Sep 20 10:51:23 2020 No.12142280 suppose you have an object traveling 1 km/s and which blinks a light every second, and it travels toward you.what will you perceive its period to be and why?
 >> Anonymous Sun Sep 20 10:53:36 2020 No.12142285 >>12142280the object is traveling 1 km/s in its own frame of reference *
 >> Anonymous Sun Sep 20 10:54:26 2020 No.12142291 File: 38 KB, 362x346, 1593273044273.jpg [View same] [iqdb] [saucenao] [google] [report] >Work in hypothesis for 2 years>Might have come up with something that makes my previous paper obsoleteDid I just BTFO myself and rendered my past 2 years self useless
 >> Anonymous Sun Sep 20 11:05:22 2020 No.12142315 >>12142280The reception period would be almost indistinguishable from the emission period, because $\frac{v}{c} << 1$.
 >> Anonymous Sun Sep 20 11:05:59 2020 No.12142317 File: 83 KB, 922x593, 1.png [View same] [iqdb] [saucenao] [google] [report] Stack exchange isn't being helpful, so I am coming in a time of need to you anons. The problem is actually pretty interesting but I am too brainlet to figure it out. How do I find $S_n$ with the given information?
 >> Anonymous Sun Sep 20 11:06:25 2020 No.12142323 >>12142315would the period be larger or smaller than 1 second
 >> Anonymous Sun Sep 20 11:12:10 2020 No.12142338 >>12142323Very slightly larger.[eqn]f_{rec} = \sqrt{\frac{1-\beta}{1+\beta}}f_{em}[/eqn]with $\beta = \frac{v}{c}$
 >> Anonymous Sun Sep 20 11:20:21 2020 No.12142363 >>12142323suppose the object is 100 km awaythe first blink would be received after 1 second + 100km/300,000km = ~1.000333sthe second would be received after 2 seconds + 99km/300,000km = ~2.00033sthe third after 3 seconds + 98km/300,000km = ~3.000326and so forth3.000326 - 2.00033 = 0.999996so why would it not appear to decrease from observer's perspective?
 >> Anonymous Sun Sep 20 11:42:18 2020 No.12142410 File: 25 KB, 995x424, why.png [View same] [iqdb] [saucenao] [google] [report] mathlet here, I know the centroid "should" be at 2pi/r to work for the surface area of a sphere using Pappus's theorem, but how do you calculate it as such. Keep getting/seeing 4r/3pi.
 >> Anonymous Sun Sep 20 11:55:13 2020 No.12142441 >>12128104>>12119726Learning chemistry has this weird learning curve where you're learning physically advanced stuff without getting any basic physics. If you want to really understand what you're doing focus on physical chemistry. To answer your question: applying an electric field attracts and repels ions depending on their charge.
 >> Anonymous Sun Sep 20 11:59:46 2020 No.12142459 File: 27 KB, 700x467, Smiling British Pepe.png [View same] [iqdb] [saucenao] [google] [report] >>12142410>Keep getting/seeing 4r/3piThat's the centroid of a solid/filled semicircle. You need to use the centroid of a semicircular arc to find the surface area of a sphere.
 >> Anonymous Sun Sep 20 12:13:28 2020 No.12142486 >>12142317That's literally just a binomial distribution: $p = \pi / 4$, $n$ is the number of points. Can't you get the minimum $n$ needed from google?
 >> Anonymous Sun Sep 20 12:14:33 2020 No.12142491 >>12142486I can't just google, no. I need to calculate $n$ required by using the given bounds.
 >> Anonymous Sun Sep 20 12:30:43 2020 No.12142541 File: 86 KB, 965x452, unknown-130.png [View same] [iqdb] [saucenao] [google] [report] Can someone tell me how they got from the second last step to the last? I don't know how they pulled out the (y+y')...
 >> Anonymous Sun Sep 20 12:55:27 2020 No.12142619 >>12140140>Also, every real/complex vector space is metrizable by a norm.>Take a base. The norm of an element is the sum of the modulos of it's coefficients in the base.My God it hurts to read that.
 >> Anonymous Sun Sep 20 13:04:32 2020 No.12142643 File: 725 KB, 709x1200, 91dd7cd0225428f0395c78b306625127.png [View same] [iqdb] [saucenao] [google] [report] >>12142541$y+y'=1$, same way they knocked out the $x+x'$ term in the previous step
 >> Anonymous Sun Sep 20 13:07:31 2020 No.12142652 >>12142643sorry i don't know anything about anime. isn't this yukari? so yukari is back?
 >> Anonymous Sun Sep 20 13:09:23 2020 No.12142655 >>12142652no thats not yukari
 >> Anonymous Sun Sep 20 13:17:59 2020 No.12142676 File: 601 KB, 1548x877, Yukaristop.png [View same] [iqdb] [saucenao] [google] [report] >>12142652Are you aware of what Google is?
 >> Anonymous Sun Sep 20 13:47:41 2020 No.12142750 >>12142459Ah christ of course, thanks. I knew it had to be something simple
 >> Anonymous Sun Sep 20 14:01:36 2020 No.12142791 >>12142676and how is that different? same color palette of pinkish colors, same everything.
 >> Anonymous Sun Sep 20 14:02:39 2020 No.12142793 >>12142676also i am not googling that for the fear of death. google will remember that i am interested in anime. i'd have to use vpn for that.
 >> Anonymous Sun Sep 20 14:15:41 2020 No.12142831 >>12142791you mind rereading that and posting something else? the green dressed, blond haired girl isnt pinkish
 >> Anonymous Sun Sep 20 14:34:31 2020 No.12142885 Does MEK react in any way with LCP plastic? What is a good resource for finding out information such as this? Calling the manufacturer?
 >> Anonymous Sun Sep 20 14:56:40 2020 No.12142946 if $A\subset B$then $\exists x (x\in A\Rightarrow x\in B)$Why isn't this an appropriate answer? It seems to me that 'there exists' should be a subset of 'for all' and thus an acceptable answer?
 >> Anonymous Sun Sep 20 14:58:03 2020 No.12142954 >>12142946exists isnt a "subset" of for allthere exists an x with 1 = x = 0for all x with 1 = x = 0 we have P(x)theyre totally different
 >> Anonymous Sun Sep 20 15:00:06 2020 No.12142964 >>12142946>'there exists' should be a subset of 'for all'It shouldn't.
 >> Anonymous Sun Sep 20 15:00:23 2020 No.12142967 >>12142954idgi what do you mean by 1=x=0?
 >> Anonymous Sun Sep 20 15:06:14 2020 No.12142983 >>12142946consider the case where $A={ }$
 >> Anonymous Sun Sep 20 15:06:35 2020 No.12142987 >>121429671=x AND x=0
 >> Anonymous Sun Sep 20 15:16:03 2020 No.12143001 >>12142999new thread
 >> Anonymous Sun Sep 20 20:31:58 2020 No.12143949 >>12142363no one?
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