Math rant

[He Man]

Finding the voulme of a solid inside a solid...

4 pages of integration later, somehow all i got was the area of a unit circle. How the hell did that happen?

I might actually fail this class because of that.

Anyone else here 'math-d' out for finals?

[erkishhorde]

 

I took linear algebra and apparently it was so bad that I mental blocked all memory of the class. I swear I can't remember a single test or doing any homework for that class at all. I remember was sitting in the first day and thinking the teach was a jack ass. Other than that, nothin.  I know I passed though because it's on my transcript!

Oh yeah, just remember, anything that takes you more than 30 minutes to do probably won't be on the test (unless you just totally don't know what you're doing and that's why it's taking you so long). Unless of course your teach likes to give those 1 or 2 mega question tests. Those ones always suck.

[teddy037.2]

what is this 'math' you speak of?

[He Man]

lol, its a take home test, you figure out how hard he made it lol.

I kinda know what im doing. but i kinda dont know how i should appraoch it. im just integrating the voulme of a cyliner with rounded ends. but some how i lost my limits of the sphered end and it became a cylinder with no height, aka a circle, or in my math teachers terms, "you fail" cause circle = no area. its a circular disc. lol

[JohnnyDucati]

lol, its a take home test, you figure out how hard he made it lol.

I kinda know what im doing. but i kinda dont know how i should appraoch it. im just integrating the voulme of a cyliner with rounded ends. but some how i lost my limits of the sphered end and it became a cylinder with no height, aka a circle, or in my math teachers terms, "you fail" cause circle = no area. its a circular disc. lol

area of circle = pi*r^2

let x be the length of the cylinder, total length = big X.

volume of a "sliver" of cylinder = pi*r^2 *dx

Integrate from 0 to X:  pi*r^2*dx

V = (1/3)pi*r^2*(X) - (1/3)pi*r^2*(0)

Volume = (1/3)*(pi*r^2)*X

Right?

Wow.  That fried my brain.

[erkishhorde]

What lvl math is this? When's it due? Quarter systems ended yesterday, no? So I'm guessing your on semester system, not that it matters but that leads me to guess it's due sometime next week. Sounds like you're trying to solve for the area of a circular cylinder w/ a sphere cut out of the middle? Or are you trying to solve for the area of a capsule-type shape?

[cloudseeker]

area of circle = pi*r^2

let x be the length of the cylinder, total length = big X.

volume of a "sliver" of cylinder = pi*r^2 *dx

Integrate from 0 to X:  pi*r^2*dx

V = (1/3)pi*r^2*(X) - (1/3)pi*r^2*(0)

Volume = (1/3)*(pi*r^2)*X

Right?

Wow.  That fried my brain.

If the cylinder is constant radius, I don't think you even need to integrate.  Isn't that just pi * r ^ 2 * X?

edit:  or it has a half sphere on each end?  Then just add to the above the volume of one sphere.  (4/3) * pi * r^3, yes?

But...if you integrate, wouldn't 0 to X of  pi * r ^ 2  dx be more like  (1/3) * pi * r ^ 3?

It has been 15 years though...

[El Matador]

god I'm so happy I'm over partial differential equations. That shit is scary....

[CapnCrunch]

slap the problem up here. I work with several engineers and they love this shit.

sick bastards.

[He Man]

Or are you trying to solve for the area of a capsule-type shape?

spot on the last one, capsule type shape, kinda like the pills im taking to stay sane right now. I am in Calc III right now. Calc I and II were breeze, III is @($@ HARD!!!!

anyway, the test is due on tuesday. finals is this week and next.

The way my class works, if you get 85+ on the final, your grade is that. ive gotten 80-90 on the last  2 test, this is the 3rd one. Except this last test is make the beast with two backsing HARD AS BALLS. But after looking at all the finals since 2003, i can easily get an 70. Its the last 30 points that i need to understand (basically everything on this test)
I have my math final on thursday. physics on wednesday. 

heres the test. 



Problem 3 is the one im talking about. I tried doing it as an x simple region (or type 1 as some call it ) and doubled integrated using 0 as the lower bound, and the top of the sphere as the upper bound. becasue of symetry you can say the area of the capsule shape is 2x that. but the numbers quickly got make the beast with two backsed. the 2nd integral would be -1 to 1. however i am also thinkiing maybe i can use cylindrical coordinates. Except my what would i use as my bounds? I know my theta can be 0-2pi.

If someone is kind enough to point me to where i can learn more about convergence test or solve it for me so i can see solutions!    (ok not so much the last one, but if someone has a good tutorial site, link me!) The text book doesnt have much on the complicated stuff. But i have my basics down pretty well, but the application in more complex problems is still kinda IZ_. Wish i didnt have 2 hard classes this semester. Would of been easier.

god I'm so happy I'm over partial differential equations. That shit is scary....

LOLOL im taking that next semester, then linear algebra..... thats if i dont bomb this test. my actual engineering classes are a breeze compared to this stuff.

[CapnCrunch]

Chemical engineer David French aka. Frenchie, is on the job.

[Popeye the Sailor]

Here's one of the cheers from the college I went to.

e^x, dy dx,
e^x, dx
Cosine, Secant, Tangent, Sine;
3.14159
E-I, Radical, Pi;
Fight 'em, Fight 'em, WPI!


Yeah.

[He Man]

Chemical engineer David French aka. Frenchie, is on the job.

man chem-e's are the sickest people in the head....next to physicist....  how many engineers do we have on this forum anyway?



that is a chant atleast has school spirit... I should of never came back to NY. The story goes, every prospective engineer at CCNY will become an ME when they fail at that other engineering major and die at 30 of alcoholism. optimism?  barely any...back to grinding out math...

[Capo]

man chem-e's are the sickest people in the head....next to physicist....  how many engineers do we have on this forum anyway?



that is a chant atleast has school spirit... I should of never came back to NY. The story goes, every prospective engineer at CCNY will become an ME when they fail at that other engineering major and die at 30 of alcoholism. optimism?  barely any...back to grinding out math...

Pompetta is a Professor of Chemistry

[El Matador]

LOLOL im taking that next semester, then linear algebra..... thats if i dont bomb this test. my actual engineering classes are a breeze compared to this stuff.

Pm me next semester. My notes on DiffiQ's are what got half my class to pass the course. I can send them over if you want.