/sqt/ Stupid Questions Thread

6 letter word for 1 million ohms?
I want to say Mega, but that's only four.
Also the second letter is an e

Sound easy enough, but I haven't done that in 15 years.

Mega ohm is shortened into Megohm for easier pronounciation. Literally on Wikipedia.

Nice

Gotta start somewhere and at some point.
There are also tonnes of online resources to use like Khan Academy.

Start reading today

I'm not afraid of starting, I'm afraid of starting with the wrong thing and then quitting, and I'm not sure how to find middle ground literature that's not quite brainlet popular science shit and not quite academic research papers.

>[...] "This result is proved by constructing from the monadic-second-order sentence expressing the property and an integer that bounds the tree-width or clique-width of the input graph, a finite automaton intended to run bottom-up on the algebraic term representing a decomposition of the input graph."
Does this sentence make any sense?

The thought can actually change reality?
After quantum physics a lot of brainlets say it does, I would like to hear an opinion of a physicist on that.

What you're asking for is called a textbook.

How do I find the curriculum for whatever subject? For example, if I wanted to study biophysics. How do I find out which textbooks and the order to read them in to be a pro biophysicist?

Go to a university website. They typically have the curriculum for their subjects, and often they have recommended literature as well.
Biophysics specfically sounds like a Master's degree that you would do after getting a Bachelor's in either Biology or Physics, so you'll have to pick one of them first. Don't quote me on this though. I'm just a Computer Science babby.

How do I solve for p(0) assuming growth rate is proportional to population at time t?

When I solve for K i get -ln(5)/7 but when I plug that value in, P initial is like 800

omg im dumb nvm

People say that all the fundamental forces act at basically infinite distances, but logically couldn't you say that the influence of that force ends at the point where the acceleration is less than that required to move an object one planck length per age of universe?

>I'm afraid of starting with the wrong thing and then quitting
Work on your discipline, then read books.

So I'm a brainlet who doesn't understand how to do proof by induction. I'm trying to prove that
[math]{2}^{x} = \sum_{n=0}^{x - 1}{2}^{n} + 1[/math]. I have the base cases down, but I literally can't think of what to do for the "n+1" step. I'm not trying to ask for homework help, just for someone to point me in the right direction

>but I literally can't think of what to do for the "n+1" step.
How does sum_{n=0}^{x} 2^n+1 relate to sum_{n=0}^{x-1} 2^n+1?

multiply both sides by 2

Yeah, turns out we were actually wrong. The null hypothesis was that the mean = 8.6

Ok, that actually makes sense. Thanks.
I just wish there were general rules for this. It seems like for every proof you have to do different shit.

>waaah, my math is no longer cookbook bullshit
grow a pair you fucking brainlet

>Passively wishing something was easier
>Complaining
>The same thing

>making a post to moan about how there aren't rules for solving a problem
>passive wishing
keep it up brainlet

>yeah no rules lmao fuck tha scientific method n shit fuck the problem solving process nigga

This is math; not gender studies where you can just make shit up and still have it be valid because you indentify as a non-binary

>taking a post out of context to strawman
nice 1 faggot

can't use latex but, I'm supposed to calculate the electric field given a smooth uniform charge density rho, which is given by rho_0 (e^(-r^2))

I have some idea how to do this, but the actual integral gives me an absurd answer and so I'm stuck.

I wish gender studies was like math and I could induct the optimum number of genders for a healthy society.

I can't for the love of me figure this one out.

Any tips?

not sure if this is more Veeky Forums or /diy/ but its got formulas and numbers and stuff so im going to try here.
i have a propane furnace burner that i would like to run on oxyhydrogen and i want to build a hho generator rather than just buy it bottled. however i need to know how much gas the burner consumes so i know how much i need to generate. can someone help me calculate this?

We're not helping you with some shitty OC you fa/tg/uy.

??

A dodecahedron is also known as a d12 (a twelve-sided die) and is used in many tabletop games.

Well using this, instead of a 3-d diagram I got a max of six red faces from trial and error.

It'd help a lot if we knew what maths this is suppoded to pertain to.

dude dont be a pussy. i didn't read for ten years and the most i took in high school was trig. what a joke. i spent most of my time in between then doing drugs and working minimum wage jobs. you know what i started with? motherfucking papa rudin. shit kicked my ass but i literally opened up that book starting from the end and working my way to the beginning and read it every fucking day until ideas started popping up in my head and i started remembering how to actually think again. now proving theorems from rudin are trivial exercises and i can browbeat grad students on MO whenever i want. did i mention my dick grew while i was reading rudin? point is, read things that are way above your level until you "Get it". teachers and students will tell you to start with someting easy and gradually work your way in. its bullshit peddled by people who don't want you competing with them. start with the hardest book and bang your head against it until win. its not easy, and you need brass balls to endure the pain of feeling stupid for long periods of time, so stupid it hurts and you want to die, but if you stick with it, you will come out ahead of everyone who fell for the "Start with khan academy" shit. seriously, if you can beat the feeling of stupidity, and you always start with the hardest text on the subject every other text is easier and when you eventually go back to the beginning you will blaze through it realizing what all of it is eventually for because you remembering asking yourself for hours on end and weeks on end what the fuck this stupid fucking theorem meant. it will all click. trust me. did i mention grad students are pussies? dont trust them. they're soft. they need their hands held all the time. little babies. immerse yourself in the hardest most obscure technically demanding research possible and don't give up. that's the best advice you can get. don't. give. up.

>dude dont be a pussy. i didn't read for ten years and the most i took in high school was trig. what a joke. i spent most of my time in between then doing drugs and working minimum wage jobs. you know what i started with? motherfucking papa rudin. shit kicked my ass but i literally opened up that book starting from the end and working my way to the beginning and read it every fucking day until ideas started popping up in my head and i started remembering how to actually think again. now proving theorems from rudin are trivial exercises and i can browbeat grad students on MO whenever i want. did i mention my dick grew while i was reading rudin? point is, read things that are way above your level until you "Get it". teachers and students will tell you to start with someting easy and gradually work your way in. its bullshit peddled by people who don't want you competing with them. start with the hardest book and bang your head against it until win. its not easy, and you need brass balls to endure the pain of feeling stupid for long periods of time, so stupid it hurts and you want to die, but if you stick with it, you will come out ahead of everyone who fell for the "Start with khan academy" shit. seriously, if you can beat the feeling of stupidity, and you always start with the hardest text on the subject every other text is easier and when you eventually go back to the beginning you will blaze through it realizing what all of it is eventually for because you remembering asking yourself for hours on end and weeks on end what the fuck this stupid fucking theorem meant. it will all click. trust me. did i mention grad students are pussies? dont trust them. they're soft. they need their hands held all the time. little babies. immerse yourself in the hardest most obscure technically demanding research possible and don't give up. that's the best advice you can get. don't. give. up.
cringe

Not as cringe as quoting the entire goddamn paragraph.

Any recommended path to take if I want to learn rigorous computer science mathematics and concepts from a software engineering background? Typical online resources tend to overlap and I'm not sure in what order I should be going

this presentation is fucked up. are they trying to spread disinformation on purpose?

the yellowed part fucks everything up when N.H gets anywhere near zero, and on rough materials it's messed up throughout the entire range.

Believe it's graph theory. It's from a problem solving course where we look at many branches of mathematics.

what the fuck is the difference between a sheaf a level set and a section? because i can't tell the fucking difference and it seems like everyone is making a huge deal about something that is not mind blowing. anyone?

a sheaf is a functor
a level set of a function at a given value is the set of all points in the domain of a function where the function takes on that value
a section is a right inverse

How do I calculate the force necessary for a sharp edge to press straight through a material, without slicing or sawing?
Pic related, for example.

then why do illustrations of sheaves always look like level sets

>then why do illustrations of sheaves always look like level sets
example?

how many ounces of lemon are there in an ounce of lemonaid if we assume a quarter inch thick rind

also how many ounces of water to lemonjuice

You either need the brittleness value (from the charpy v-notch test)
Or dive a bit deeper into fracture mechanics I guess.

>need the brittleness value (from the charpy v-notch test)
I can't seem to find a table of brittleness values or Charpy test results online anywhere.

Hey Veeky Forums i am a brainlet in finding the derivative of inverse trigonometric and logarithmic, can anyone lend me a hand about it?

use mathematica/wolframalpha

If I swap the upper and lower indices of a tensor is it still a tensor? Always? Or only sometimes? E.g. I have
[math]
T^{i_1,i_2,...,i_\mu}_{j_1,j_2,...,j_\nu}
[/math]
and I turn it into
[math]
T^{i_1,j_2,...,i_\mu}_{j_1,i_2,...,j_\nu}
[/math]
I feel like this would be a common question but I can't find anything about it.....

What kinda material are we even talking about?

Wood. Different kinds have different strengths, but for starters I'd take any wood at all.

I'm trying to calculate how much force is necessary to push a blade through a thin trunk/thick branch, severing it completely.

So in any case you'd be going perpendicular to the fiber. I've googled the "Scherfestigkeit" (German for shear strength) of wood just now and I've found perpendicular values for two types wood. 22 N/(mm^2) of cross section for spruce, and 35 N/(mm^2) of cross section for beech. It's lower parallel to the fiber, but you wouldn't cut branches like that.

holzunddesign.wordpress.com/2014/05/14/holz-an-sich-holzfestigkeit/

Itself apparently quoting the book "Der Tischler 1", publisher Bohmann in Vienna (A), 1990.

So the total force needed to cut through a given piece of those woods is the Newton value x the area of the cross section of the piece of wood?

Yes, like that. I'm a steel construction draftsman and at least that's how it works for cutting of low diameter rods and such. From my judgement the principles are the same for wood, only with different values and with attention to fiber direction, and the literature backs it up.

I may have my math wrong.
From what I can tell, cutting a 25mm branch of beech, the cross-section of which would have an area of 490.87mm^2, would require 17,180.45 Newtons.
That seems extraordinarily high. Is there something else I need to factor in?

Either the high force necessary is counteracted by the leverage of the long cutter handles, turning a high force low movement momentum into a low force high movement momentum, or it does in fact work differently because wood never shears as a whole, only in small sections. But then why would these values even exist in books for carpenters and cabinetmakers?

Bronies exist, why?

Some people do really like pastel cartoon little horses.

NEXT.

If [math]A_{n} = [0, \frac{1}{n}][/math] for each [math]n\in \mathbb{N} , would

[eqn]\bigcup_{n=1}^{\infty} A_{n} = \left \{1,\frac{1}{2}, \dots , \frac{1}{n-1} \right \}[/eqn]

[eqn]\bigcap_{n=1}^{\infty} A_{n} = \varnothing [/eqn]

?

lets try that again

If An=[0,1n] for each [math]n\in \mathbb{N} [/math], would
[eqn]\bigcup_{n=1}^{\infty} A_{n} = \left \{1,\frac{1}{2}, \dots , \frac{1}{n-1} \right \}[/eqn]
[eqn]\bigcap_{n=1}^{\infty} A_{n} = \varnothing [/eqn]

?

no, that union and intersection are both wrong, I'm not sure how you came up with those answers but try them again

also try drawing a picture

how about for [math]A_{n} = (n,\infty)[/math], then [math]\bigcup_{n=1}^{\infty} A_{n} = \mathbb{N}\setminus {1}[/math]

[math]\{1\}[/math]

this is also wrong

how does the interval work in this problem?

how did you get the answer you got? I'm not sure if you don't understand what a union is or what an interval is

I was working on a false understanding so I really don't know now

The union is [0,1] since [0,1]=A0 and An is a decreasing sequence of subsets.
The intersection is {0}, since 0 is obviously an element of each An but for any other number ε in (0,1] you can find an An which doesn't contain ε.

Not even close.

I think it would be either one doesn't see Saturn, the stars are different, or the planet looks shifted left/right depending on where they are

> I got a max of six red faces from trial and error.
Not sure what you meant by "trial and error", but there are 2^12=4096 possible ways to paint 12 faces with 2 colours.

That's small enough to enumerate the cases in software and determine that none of the valid combinations (where every vertex has at least one adjacent black face) have more than 6 red faces.

But that's probably not going to be accepted for the "explain why" part.

One thing to consider is that a dodecahedron is dual to an icosahedron, so the question is equivalent to colouring every vertex of an icosahedron red or black and finding the maximum number of red vertices given that every face has at most two red vertices.

Someone said something to me and I'm having a fucking crisis right now.
Is math a liberal art?
It does not exist without people.

if a black holes gravity can absorb light, it means that light has mass. when light has mass how can it travel at lightspeed? how can light violate physical laws?

gallier's book and this other guys thesis i just found both use cross-sections/slices of functions as examples of sheaves. it makes sense considering that they are "used to track local data" i get that, but why call it a sheaf? why not just be honest and call it a cross section or a level set? we already have the concept why are we giving it a new name ad dressing it up in "new" theory! why do the french insist on ruining math?

Can someone put into context the power output of today's experimental MFC (microbial fuel cells) compared to traditional power generation methods?
I don't really know how much either produce on average currently, and I was curious how the new technology is coming along.

>capital letters after ">"
Fuck off to Brainlet.

>It does not exist without people.
Prove it.

>if a black holes gravity can absorb light, it means that light has mass. when light has mass how can it travel at lightspeed? how can light violate physical laws?
Light have energy. Energy, like mass, can bend the space. If energy can bend the space, it's also affected by the bending of the space. That's why light is affected by gravity without having mass.

>this presentation is fucked up. are they trying to spread disinformation on purpose?
What do you expect from a place like this?

Because there wouldn't be people around to execute it? I think?
This isn't my argument, don't ask me to defend it. I want you to counter it.

>Because there wouldn't be people around to execute it?
Are you claiming that people are the only intelligent beings in the universe?
>I want you to counter it.
I'm not claiming that it's possible to counter it.

Is being generalized as smart damaging to a person's psych? Doesn't it essentially mean you look like a nerd? I get this all the time and I do not think I'm anywhere near "smart", I get good grades for example but that is only because I put a lot of effort into my work, probably more than a naturally smart person.

Is it reasonable to assume that all life in the universe has the same goal as terrestrial life, and that evolution and darwinism would be in effect elsewhere (at least until the appearance of intelligence life that can consciously ignore said principles), or is the assumption just indicative for a limited human horizon?

For various reasons, I fucked up my linear algebra course and on top of never even reading the chapters on inner product spaces and spectral theorems, I have only a weak grasp of diagonalizability and Jordan normal form. Over the next two years I'm going to be doing a fucktonne of statistics and mathematical finance, with a touch of pure mathematics (specifically, metric spaces and Lebesgue integration).

Does it sound like those gaps in my knowledge will ever come back to bite me?

Local Buckling is a failure mechanism that is almost always achieved prior to failure in shear, especially in the manner we are discussing.

regardless of the force you have calculated, the area where pressure is applied (and therefore that can be reduced to a resultant force) is very small - so a relatively low moment on the arms of the cutter produces large *pressures* that leads to local buckling and hence shearing of the wood.

Ergo the actual cutting force required is not so high as one might initially expect, based on pure shear failure calculations.