annndddddddd i have another question

so the force on a current carrying wire while its under influence by a magnetic field is directly proportional to the length of the wire?

The longer the wire, the more stuff exposed to magnetic field

@0celo7 I am very happy you got it; I'm not sure about what exactly it was about anymore, but surjectivity should definitely be the case if we take the - now I'm actually missing the right mathematical terms in english, sorry :( - well, let's say if we take the $^C$ in the domain and then invert - otherwise it does not really make sense, does it?

anyway, sorry, my math classes were one of the few things where I stuck to german literature, so I'm a bit lost for words

but I'm happy you solved it :)

@Sanya The ${}^C$ is the complement in English, too

@ACuriousMind I didn't want to mention that I'd forgotten the german name too

Haha, okay :D

my last analysis class was in 2012 I think

or 2011

oh ok

afterwards I only did algebra as a minor in the master degree course but well ... no functions there

Help

I am cold

Someone expand the sun

just polute more

engulf the earth in flames

Sorry I'm an energy drink man

Current progress: en.wikipedia.org/wiki/Homotopy_group

^me

on the right

when do they teach you cross products?

like, vector cross products

i have no idea how to take them

sal khan on khan acadmey is treating the length of a wire as a vector quantity and taking the direction of the length

when do they teach cross products? depends on your country

and the subjects you study

but usually in your first physics course

it's basically just multiplying the components that are at right angles to one another

Cross product was like early university here, I think

Like first year I think

i am 10th grade so maybe i should just ignore em lol

depends on your ambition

he is using the right hand rule anyway so i understand

ambition?

well...i like physics

ambition = how successful you want to be

an example of cross products is the area of a square

i wanna be like elon musk

ye

you take one length and mulitply it by the other length that is perpendicular to it

i think its related to directions too..

yes you only multiply together the perpendicular components

like, multiplying 2 or more things involving vectors and then figuring out if the product is a vector or not and if it IS a vector then figuring out the direction

yes

the right hand rule

there are several different "right hand rules" that all acheive teh same result

I believe sal kahn goes through one in the video

yea

e.g. suppose i want to compute X cross Y

fleming's right hand rule

and X is a vector pointing to the right

and Y is a vector pointing up

then X cross Y will be a vector pointing out of the screen

90 degree between em

and Y cross X will be a vector pointing into the screen

oh

oo dats complicated

but cool

k thanks again!

np

to everyone

lol

I need some help here..... I was almost driven crazy...

I am working on a problem: design an RC low-pass filter that has $V_{out}/V_{in}=0.5$ at 5kHz

my answer is: $RC = 3.46\cdot 10^{-4}$

but the answer said 5.5 x 10 ^(-5)

it is a straight forward calculation, I don't know where is wrong...

@Shing Since you haven't told us anything about how you computed that number, we can't tell where you are wrong (or not) either

@ACuriousMind I simply used the equation $V_{out}/V_{in}=\frac{1}{(1+\omega ^2 R^2 C^2)^{1/2}}$

um... wait I think I made a stupid mistake

the omega is angular freq....

damn

I was about to remark that the ratio between your two results was suspiciously close to $2\pi$ ;)

lol thanks, man.

so I'm working on Euler problem 8

and I really have no idea how to even start solving it.

it isn't a matter of writing the code, its a matter of figuring out how to do it.

my initial idea was to make the number a list and iterate through it

but I'm not so sure it'll work like that. I think I need to somehow multiply every set of 13 adjacent numbers, but how to do that, I'm not sure.

Hello fellow humans

@BernardMeurer, hello

@MAFIA36790 Probably playing fallout or sleeping

Caption: Current progress before starting Lie groups proper

Comment: Most algebraic topology and algebraic number theory group articles are incomprehensible

Current location: Hyperbolic group

I'm beginning to feel I have a problem and should seek professional help ...

what's with all those laptops?

Why are operators always defined on a subspace of the Hilbert space

Why not the whole space

@JohnRennie, that's not a problem

that's just awesome

They're all mofo 3GHz i7s as well :-)

But I have seriously got to resist the temptaion to buy more :-)

=D

I have my own set of problems

like an addiction to books

especially nonfiction now

@MAFIA36790 sell my babies? You're a sick man!!

I also spend way too much time coding to solve arbitrary problems

like the Euler problems

but I just can't resist

also python...I <3 python

The set theory book? I am indeed reading it

it is fabulous

thanks again for the recommendation

=D I can't wait

@Kaumudi shrug :-)

@Kaumudi, hello

@Kaumudi hi

@Kaumudi, pretty well. I've gotten re-addicted to the Euler problems. I'm reading through Naive Set Theory. and I'm also procrastinating.

@Kaumudi I'm just in the math chat room

Procrastinating on many things, actually...

@Kaumudi, yeah...it is good while it lasts, and then you have to do everything all at once =( but anyway, I might start working on it now

hmm, what is it?

okay, will watch, thx

hello

I'm sick, not sure what to do

Just slept for 11 hours

And I should be hungry, but I'm not...

Cold, I hope

I don't think it's a fever

I sleep 7-8 hours every day, I'm not sleep deprived.

It was because of the cold, I went to bed early

Because of the cold

I also just coughed up some mucus the size of a silver dollar...wtf

@Kaumudi Do you think that's sleep deprived?

If anyone is interested, the current Perimeter Institute public lecture is on dilatant suspensions. I did a lot of work on these while I was working at Unilever Research.