/SQT/ - Ask your Questions Here

Mathematics, Physics, etc.

Other urls found in this thread:

wolframalpha.com/input/?i=sum sin(pi/(n log n + n log log n )) from 1 to infinity
en.wikipedia.org/wiki/Prime_number_theorem#Approximations_for_the_nth_prime_number
twitter.com/SFWRedditImages

For random variables I am trying to understand what the below equation means:

Pr[X=v] := Pr[X^-1(v)]

Is it basically saying the probability of v in set V is the same as the probability of falling into the pre-image of v in set U?

I can't do this fucking question
I'm not sure how to interpret it in the first place. I'll upload my working in a sec
I must be making a wrong assumption somewhere

...

turns out I didn't know what the com energy was

What is the path I should follow to be in the top 1% students of my department?

Undergrad physics here.

Are there any mnemonics for the construction of ray diagrams for convex/concave lenses and mirrors? Just purely introductory stuff.

Why does Faraday's and Amperer's equations have symetry in maxwell's equations, but not Gauss's laws for electricity and magnatism?

What do you mean symmetry?

...

If there were a cut and dry path, don't you think everyone would be doing it?

In the second equation, you could set up a symmetric variant, by setting it not equal to 0, but to some term corresponding to a "magnetic charge", just like you have the electric charge in the first term. This would, as far as I know, form a consistent mathematical and physical model.
However, we don't allow magnetic charges, as this would correspond to magnetic monopoles, which we do not usually observe.
Hope that's not too wrong!

Thats what i mean. Polarity of electricity and magnetism is not symmetrical. Why?

Because they are not symmetric phenomena. You'll find that special relativity handles electricity and magnetism in a very neat unified way, which I feel makes it very obvious why this asymmetry is justified. Basically, magnetism is more or less dependent on electricity, it results from movement of electric charges and nothing else, which is exactly what Maxwell's equations say if you analyze them in detail.
Probably not the most satisfactory answer? I'll let someone smarter than me handle that, but ever since I heard a good lecture about special relativity I always felt very at peace with the asymmetric properties of electricity and magnetism.

Because you shouldn't treat electric and magnetic fields as separate objects. Maxwell's equations look much nicer when you unify them.

Not necessarily. There are cut and dry paths to getting fit and not everyone is doing it.

If gases like to have uniform density in a container, how come the universe doesn't act like a container?

Thank you. So magnetism is a consequence of electrical "activity," so its not going to necessarily be symmetric.

I dont know how to do this yet. Im finishing up Physics 2. I dont think Ill ever get that far into physics because I was just accepted into the MechE program. The only classes ill go this far into electromagnetism is circuits and maybe materials and thermo, but i doubt materials and thermo will cover much of electromagnetism.

What I should know before taking mechanics of materials? I fucked things and I ending taking it before multivariable calculus and differential equations. Are those classes really important? or I need take them before?.

...

x=10; you have to repeatedly complete the triangle angle, interior angles always add up to 180, then you get to the last 4 unknown angles and you have to set up a system to get them all in terms of x and then bisect one of the triangles to create a right triangle and solve. At least that was how I went about it w/o trig. Hope that helps

What are you smoking?

I think you ahould learn how to /math/

Afaic lots of undergrad physicis math can br derived from simpler stuff with calculus so you dont havr to remember the whole book going into tests. Also shows that you are not just a nigger memorizing texts so whoever is checking youe test will be impressed at least

Nice. Looks like we're taking the same class senpai

Can I ask a question?

Engineers built the PC you are shitposting on right now, so...

Mathematicians and scientists made computers possible.

my question

Why the fuck would you need to "reinvent" the entire math and make it math 2.0? That makes no fucking sense. It would be just exactly like it was with calculus when it was first invented, it was just a new way of doing math, it was still math, it wasn't math v1.1 or some bullshit.

Basically what I'm trying to say is, we wouldn't need to "reinvent" math, but rather invent new math and add it to already existing knowledge of math.

Is speed how quick/fast/rapid something is moving, or is it how much distance something covers in some time? (fuck off with "it's a magnitude of velocity", I already know that and it's merely one of the book definitions)

the former, though with constant speed the two are indistinguishable

Thanks!

>or is it how much distance something covers in some time?

what units do we measure speed in user?

mg or %, depending on if you mean dosage or purity

For ease of typing just read = as a triple bar.

It seems that na^d = 0 mod a^d and of course a^(dn) = 0 mod a^d, but only if n is a natural number. Do modules only work with natural numbers, or am I just being stupid?

Just use ≡

[math]na^d \equiv d \mod a^d[/math]
[math]a^{dn} \equiv 0 \mod a^d[/math]
[math]a \in \mathbb{N}[/math]

How do you compute [math]\int \hat{r}dt[/math]?

[math]\hat{r}[/math] is the unit vector in polar coordinates.

I managed to find the answer, but only is [math]\dot{\theta}[/math] is constant

How is the unit vector changing with t?

[math]\dot{\hat{r}}=\dot{\theta}\hat{\theta}[/math].

Is that what you're asking?

Just started a Calculus 2 course and the professor (infamous for being shit) started the first day with a bunch of random shit that looks nothing like calc 1...(some sort of rotating 'slices' of a cylinder in a graph and then finding its volume by integrating bullshit)

What do

Give us a less ambiguous question. Spoiler alert: Calc II is the hardest calc course you'll take and III will be a breeze compared to it.

Sorry, yeah I've been hearing that from everyone around, but I'm scared because im juggling physics and a few other classes along with calc II

I just want to know what topics I should start trying to learn from now so I don't die

Volumes using cross sections? I'm pretty sure that's what's you're doing

Volumes using cross sections is from Calc 1

I want to get a headstart on my C++ class next semester.
Where should I start? Can you recommend me a text book?
This will be my first computer language

Well I just finished calc II and he literally just described what I did in the first lesson

Thanks for the lead, better than the "just slice shit up and integrate" explanation the professor gave.

You should try something like hackerrank.com where you can do a bunch of problems for c++ (and other languages) from the very basics.

Also YouTube tutorials I guess

Does it matter which school you go to?
I have 2 choices right now: One is a science and engineering school, the other is just a regular 4 year university, however in terms of engineering schools in my state, this school places a little lower than the Science/Engineering school.
I really want to go to the Science/Engineering school, but this one is a bit harder to get into. I also like the campus a lot better than the other. Is it really just school?

Just take the former m8. It's a fucking no brainer.

Do you think its possible to finish a Calculus course and a Physics course over the summer?

I decided to change my transfer school to a much better school and that I like more. If I can manage 5 classes each semester, then I can transfer there in 3 more semesters. This is only possible if I am able to complete these 2 courses in 5 or 6 weeks.

If possible, I would like to get a head start. What are some good calculus textbooks? I heard Spivaks Hitchhikers guide was good but I can't find a pdf for it.

Would you die if I pulled off the Riemann hypothesis?

Picking one with a nicer campus or where you think you'll fit in better is always a good idea. It won't make a huge difference which school you got to.

So is can you only use modulo arithmetic with natural numbers, or is it only in this particular case?

According to some logic manual exercises,
{Mercury, Earth} and {Mercury, Earth, {}} aren't identical
but I thought all sets contain the empty set

They aren't identical.
It's true that {} ⊂ {Mercury, Earth} (empty set is a subset of it)
but not that {} ∈ {Mercury, Earth}
This is because {} is a set of nothing, it is not nothing itself. It's kinda like how {{}} =/= {}
{Mercury, Earth} contains nothing as well as Mercury and Earth but it doesn't contain a set of nothing
Elements in the set {} are contained in {Mercury, Earth} but the set {} itself isn't contained, unlike {Mercury, Earth, {}}

>but I thought all sets contain the empty set
as a subset, but not as an element

sum [n=1..infinity] (sin(pi/nthprime(n)))

Does it converge? n=1..10^6 gives a small value of 8.822...

>want to transfer to 2 different schools
>same majors but each school requires a different science: chem or bio
wtf do i do? I'm planning on taking computer engineering and the school I REALLY want get admitted in requires chem. Also I read a [spoiler] reddit [/spoiler] post from the universities board and someone said they're packed with computer engineers. Should I still try applying? Of course, I still have 1.5-2 more years to finish my prereq courses.

Yes, exactly.

>n=1..10^6 gives a small value of 8.822...
so does [math]\log(10^6)\approx 14[/math], and yet [math]\log n[/math] diverges.

I don't know if this is a satisfying answer, but according to Wikipedia, the nth prime number is bounded above by [math]n\log n + n \log \log n[/math] for n>5. Substituting for the prime, the series diverges according to wolfram alpha, which would suggest your series diverges as well since after a few terms its terms converge more slowly.

wolframalpha.com/input/?i=sum sin(pi/(n log n + n log log n )) from 1 to infinity
en.wikipedia.org/wiki/Prime_number_theorem#Approximations_for_the_nth_prime_number

What are the potential dangers of AI? you hear musk and hawking say it's scary, but why tho?

There's nothing to worry about, the AI takeover will be glorious. The limits of human stupidity will finally be surpassed.

What's cal grant b - subsistence and fees? I accepted both on top of my pell grant. Tuition is 7k, but all three of those financial aid goes to 12k. Do I still get all the money?

there is no royal road to geometry

The potential danger is that it will kill everyone on earth, or take over human society, or something similar etc etc.

Its mostly bullshit popsci fearmongering. Very very very low chance of any of that ever coming close to happening.

By the comparison test sin(pi/p_n) diverges if 1/(p_n log(p_n)) diverges.
Now use the asymptotic expression for the nth prime p_n ~ n log(n).
You get 1/(n log(n) log(log(n)) + n log(n)^2)
Again by comparison this diverges if 1/(n log(n) log(log(n))) diverges.
Now by the integral test that diverges if the limit of log(log(log(n))) goes to infinity as n goes to infinity, which it does so the original series diverges!

Give me one good reason why this won't happen once we manage to create an AI more intelligent than a human

Help me understand gauss-bonnet formula. I don't get why it works and I don't get geodesic curvature.

Also whatever geodesic curvature is I don't understand why boundaries of caps on picrelated have different geodesic curvatures (they should since areas are different).

Currently doing my under grad in computer science and mathematics in my second year, but my question is what field of mathematics best compliments my studies in computer science. I've decided to focus on database management to hopefully become a DBA so which field of math goes best with it?

Yeah, it's a weed out course.
>Did you take Calc AB
>Did you take Calc BC
>If Calc AB=0, Then proceed to bang head against wall
AB tought you Cross Sectional Volume

IF we can create an AI smarter than humans. Theoretically if that was possible then what would even motivate an AI to start exterminating humans.

Yeah modulos only work with whole numbers, so natural numbers and integers.

I would use AI to establish the global communism :3

>engineers built the PC you're using
That would be physicists and mathematicians who made it possible. Engineers just took glue the parts together.

Will applied mathematics with some coding projects allow me to get a job as a programmer?

Well, why would the AI want to kill us? Why woudl the AI want to take over? How would it get the capability to do either of those things? Why would we make it with the capability? Why would we even bother to make an AI capable of wanting to or becoming capable of any of those things?

I mean, if we want a terminator scenario, there first has to be a prototype robot(s) made before the AI is even up and running that would be able to operate an entire robotics factory to multiply.

There are a fuckton of limitations on what a strictly non-corporeal being created and restricted by human behavior. Lets assume that Ultron gets onto the Internet. What's it gonna do? Shut it down? Remote access something that it realistically has no power to remote access? Even if it gets shut down, its a minor setback. We can just make a separate network and quarantine the AI.

There are just way too many hoops to jump through before an AI could ever become sentient, self-developing, self-sufficient, motivate itself to hate humans, and then find the capability to do something about it.

tl;dr its popsci. Movies taught you that AI is a danger. Its not.

No, modular arithmetic works much more generally than this. It's not interesting, say, in the rational numbers because every nonzero number has an inverse.

>implying they would exterminate us out of hatred or fear
There's simply more efficient uses for hydrogen, oxygen and carbon

An Ivy League uni professor just committed my private code which I shared with him via e-mail to his group's GitHub repo as his own.

I'm a PhD student at a different university.

What should I do?

pizza deliveries

Nothing at all. Keep writing code, I guess.

Where's the nearest black hole

yo momma's ass

Any of you people can provide some insight about Engineering Physics as a degree?

> inb4 it's a meme

I know that I just want to know if I'm going into the right meme

You have the electronic record of this event occurring take it to the authorities

How can I make the most out of my time in University studying Physics? How can I make the most out of it in the private sector?

Who is the first representant of a species and who does it reproduce with?
>there's none, it's a genetical continuum
Okay but what about species that don't even have the same number of chromosomes? How does an individual of the species that has more or less chromosomes than normal manage to reproduce, eventually forming a new species several generations later?

Two organisms don't have to have the same number of chromosomes to reproduce with each other

you guys know any free software that can simulate electrohydrodynamics.

also any good electrical engineering and physics texts with a focus on magnetic circuits, ionization and electric fields.

Aw, for some reasons I thought they did. Thanks user

Is this correct? The guy I'm watching solve these went by some different approach, but we both got the same result.

I'd go with the other guy's approach if it's not upside-down

>[math]\infty - \infty[/math]
>infinity times 0
>[math](x+1) - (x-1) = 0[/math]
Yeah, you should probably listen to that other guy

>How can I make the most out of my time in University studying Physics?

By thinking outside the box and looking for industry internships for the summer so that you can secure yourself an actual physics position when you graduate and not end up as a teacher.

>How can I make the most out of it in the private sector?

Now do the opposite. While working stay in touch with academia. Maybe find a way to get a masters degree with your company paying for it and/or promising you a better position after acquiring it. If not then study part time anyways to get a masters degree to climb up the industrial ladder with your education. Getting an MBA is also fine.

I just realized what I did... it's too late to do math anyway.
>hey, I hab an idea, we god a walue of 1, why don't we just go ahead and muldibly id by 100000 and ged a million! :DDDD

>That would be physicists and mathematicians who made it possible.

lol, not even close m8. innovation happens in industry out of necessity, and its done by engineers. heres how the discovery pipeline really works.

>industry engineers discover something through educated guesswork/trial and error
>give a bunch of funding to a university and they have some physicist/math guy construct a rigorous framework that defines the phenomena.
>send it back to industry where engineers refine and reiterate

friendly reminder engineers were building functional steam engines long before the laws of thermodynamics were even conceived.

>industry internships.

I'll make this a top priority, thanks.

This, but consider asking him to give you credit first. If you don't mind him using the code it could be better for you.

More of a broad question, but how much material is in a calc1 course compared to say trig or precalc. I haven't taken math since highschool and I need to catch the fuck up on math if I want to graduate any time soon. I've spent the past month and a half grinding through through reviewing Alg I, learning II, Trig, Stats and just finished Precalc. I've been studying around 2-8 hours a day and I'm wondering if it would be reasonable to complete Calc 1 as well before I take a placement test at the end of the month, or should I just cool it and enjoy the rest of the summer? That said I don't hate the studying.

I keep reading that "calc is hard" but I read the same things about precalc and finished that in 4 days. Is it actually hard?