[ 3 / biz / cgl / ck / diy / fa / ic / jp / lit / sci / vr / vt ] [ index / top / reports ] [ become a patron ] [ status ]
2023-11: Warosu is now out of extended maintenance.

/sci/ - Science & Math

View post   
File: 730 KB, 600x4203, heat.jpg [View same] [iqdb] [saucenao] [google]
4445558 No.4445558 [Reply] [Original]

Hey /sci/
I've got an integral to solve involving radiative transfer.
To simplify what I've been given, the integral is essentially
> dx/dt = -x + C
I've tried to solve by substitution, separation of variables, and by a guess and check to no avail.
Any thoughts of how to tackle this problem?

>> No.4445577

1/(-x+C)dx/dt=1
-ln(-x+C)=t+k
yes no?

>> No.4445589

> radiative transfer

trying to make a hydrogen bomb

reported for illegal content

also <span class="math">x = Ae^{B-x}[/spoiler] for some A, B

>> No.4445591

dx/dt = -x + C
dx/-x = Cdt
dx/x = -Cdt
lnx = -Ct
lnx= ln(e^(-Ct)
x=exp(-Ct)

>> No.4445593

Not sure.
The integral given is
dI/d[tau] = -I + S
Where I = intensity, tau = optical density, and S is the source function.
The integral assumes S to be constant, and to be solved as I vs tau, with an initial value I0

>> No.4445599

>>4445591
This is what I had when I tried to do separation of variables, but I was unsure if it was mathematically sound.
Wouldn't the second line be
>dx/-x = C/x dt

>> No.4445612

>>4445599
yeah it would be, thats why you need to divide the whole thing by (-x+C), look to >>4445577

>> No.4445613

>>4445599
yeah, disregard my post, I fucked it up

>> No.4445622

>>4445612
So is k just a constant then?

>> No.4445630

These can also end up being more complicated. This is a linear differential equation.

Here is a quick tutorial.

>> No.4445634

>>4445622
yup, constant of integration

>> No.4445657

>>4445634
I don't think that works for this situation, but I could be wrong.
The final answer should be some form of x = t, and x0 is what initially enters the system.
There are also limits for t >> 1 and t << 1

>> No.4445688

>>4445630
what tutorial?

>> No.4445725
File: 65 KB, 818x1058, 1278570712141.gif [View same] [iqdb] [saucenao] [google]
4445725

>> No.4445741
File: 29 KB, 600x600, 1278310223084.gif [View same] [iqdb] [saucenao] [google]
4445741

>> No.4445763
File: 70 KB, 1000x695, 1278570063818.png [View same] [iqdb] [saucenao] [google]
4445763

>> No.4445768
File: 23 KB, 333x333, 333.jpg [View same] [iqdb] [saucenao] [google]
4445768

Hello /sci/
I attended an intelligence test earlier, and I got accepted into round 2, which is the final.
I was wondering, are there any resources or anything else, to prepare me for taking an intelligence test ?
Picture unrelated.

>> No.4445771

>>4445768
Yes, you should be able to solve the integral in the OP.

>> No.4445774

>>4445771
Welp, i am unable to delete my post.
I forgot to select New Thread.

>> No.4445784

>degrees Kelvin

>> No.4445787

>>4445774
Thanks for playing and goodluck with that intelligence test.

>> No.4447114

Only ºF and ºC have a "degree". Any Kelvin temparature is represented as K only. This infograph (OP figure) is totally wrong...

>> No.4447147

>>4447114
Plus it lists the coldest temperature ever reached as 459.6 F.
Thats like twice as hot as my stove in the morning.
Nobel prize here i come