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?
[laugh]
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. ;D 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.
what is this 'math' you speak of?
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
Quote from: He Man on December 13, 2008, 05:06:19 PM
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.
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?
Quote from: JohnnyDucati on December 13, 2008, 05:30:08 PM
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...
god I'm so happy I'm over partial differential equations. That shit is scary....
slap the problem up here. I work with several engineers and they love this shit.
sick bastards.
Quote from: erkishhorde on December 13, 2008, 06:29:20 PMOr 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. [bang]
heres the test.
(https://farm4.static.flickr.com/3065/3106641522_bd64a40c2a_b.jpg)
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! [thumbsup] (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.
Quote from: El Matador on December 13, 2008, 07:12:06 PM
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.
Chemical engineer David French aka. Frenchie, is on the job.
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.
Quote from: CapnCrunch on December 13, 2008, 09:13:56 PM
Chemical engineer David French aka. Frenchie, is on the job.
man chem-e's are the sickest people in the head....next to physicist.... [laugh] 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...
Quote from: He Man on December 13, 2008, 11:45:05 PM
man chem-e's are the sickest people in the head....next to physicist.... [laugh] 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
Quote from: He Man on December 13, 2008, 08:36:45 PM
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.
;p PM'ed, i could look over them now so im a little ahead in the class.
Structural engineer (fresh outa grad but STILL not done w/ my thesis [bang]) here.
What textbook are you using? Wont' help you much if I dig through my text book and it's the same one you're using.
Oh yeah, that last one = WTF ??? It's only a 3 line question and it still has at least 6 words I don't recognize. :(
Quote from: erkishhorde on December 14, 2008, 10:02:09 AM
Structural engineer (fresh outa grad but STILL not done w/ my thesis [bang]) here.
What textbook are you using? Wont' help you much if I dig through my text book and it's the same one you're using.
Oh yeah, that last one = WTF ??? It's only a 3 line question and it still has at least 6 words I don't recognize. :(
we arent really using a text book. i just haveone as reference. Everything comes out of his mouth whic his why i dont get this stuff. He goes off on tangents worst than I do. lol talking about victorian english and his home town of birmingham for about half the class.(hes also Jamaican so it makes him have a very intresting personality and teaching style cause hes also english)
Quote from: He Man on December 13, 2008, 11:45:05 PM
man chem-e's are the sickest people in the head....next to physicist.... [laugh] how many engineers do we have on this forum anyway?
I'm an engineer. There are a lot of us here.
I play an engineer on TV.
Heh
I got my A.B. as a math major
It doesn't get any easier man
Good luck... you'll figure it out.
http://tutorial.math.lamar.edu/ (http://tutorial.math.lamar.edu/)
best website ever for upper level math!
Question for anyone who knows...
if were looking at a series such as this one (http://tutorial.math.lamar.edu/Classes/CalcII/Sequences_files/eq0108MP.gif) except the numerator was flipped to the denominator, could we still cancel out to 5/3?
Frenchie says "I forget how to do this with a double integral, but there is a down and dirty way. The intersection of the two should be two circles, x2 + y2 = 1 in the planes of z = +/- sqrt(3). So you get a cylinder, radius = 1, height = 2*sqrt(3). Then you have to integrate Pi*[sqrt(4-x2)]2, or just Pi*(4-x2) from sqrt(3) to 2 (Remember the disk method of finding the volume of a sphere from Calc II). Oh yeah, and the integral has to be multiplied by 2, because the damn thing has two ends on it."
meh [beer]
where does the root 3 come from?
If he is doing it half a circle then it should be zero no? [bang]
cause thats what i basically did. and im stuck at. lol
i just took a look at his equation again. the top part of the capsule cannot be a circle of x^2 +y^2=1. because for that to be true, it would need to be a circle, when in fact it is just a slice of a bigger circle whos radius is 2. So in reality it is just a dome.
edit: CRAZY turn of events.
After teaching my self everything on that website about infinite series. something started happening. I felt like i saw all those numbers before....
this whole test is from that website i posted above scattered from various tutorials.
Lol, so your teach cheaped out and stole someone else's stuff for his test? So that means that you've got the whole test's answers?
This is how I roll ;D
(http://img399.imageshack.us/img399/5766/tat004fl2.jpg)
Quote from: erkishhorde on December 14, 2008, 09:55:12 PM
Lol, so your teach cheaped out and stole someone else's stuff for his test? So that means that you've got the whole test's answers?
It was what i thought. its 2:15am.. and i just finished 80% of the test.
Everything is from the website basically. Except instead of X^2+1 its (x+1)^2...now it may not look like much, but it could throw a problem into the gutter and make it a) unsolveable, b) very make the beast with two backsing messy or c)pisses me off.
He has a habbit of making stuff up from his head on the board and things dont always work out the way you want it too. (inmagine 20 feet of board surrounding 3 sides of the room filled with his nonsense).
Anyway, the website i linked you guys to had enough information to teach me about everything on the test, and its been about 2 days worth of work (8+hours) to learn everything.
HOWEVER... i still cant get that capsule shaped question. LOLOL its the only thing left on hte test i for the love of god, cannot figure out. I killed almost a whole ream (500 sheets) of white paper. its all over my floor, on my bed. etc. probbaly 50 of those sheets are trying to figure out htat problem. :/
anyway, problem 1, was exactly as worded. problem 2-6 (not inlcuding 3, the capsule question) took about ~6 hours to learn and do. not bad!
okay now im back to trying to figure out problem 3.....and then physics studying and im gonna make myself a pizza and call it a morning. [bacon] does dominos deliver now?
dude is that really you?
because i drafted an idea of a tat I want, and its 3 triangles with parallel sides (to make it have some width) that are filled in with mathematics... lol
that tat is make the beast with two backsing AWESOME man. though i have no idea what it represents, i can only read it. WTF IS A GRADIENT SQUARE!!!!!
431am.
IM DONE. (not finished, aka im tired gotta wake up in 2 hours!)
Electrical Engineer here. As I started reading the thread, I started to miss the high level math classes, they made me feel a lot smarter than the mindless crap I do at work now.... but as the thread progressed and I watched He Man's slow descent into a familiar state.... I'd prefer to find mental stimulation elesewhere. Best of luck. [thumbsup]
All you have to do now is to commit it to memory so that you may instantly recall it whenever required (which probably will be very infrequent) ;D
I'm an engineer...
...and I hate shit like this. :P
I prefer big equipment building things. ;D
math is hard...
[laugh]
also, 1) what's wrong with being an ME? 2)most of the engineers i know (most of my friends) choose alcoholism as their method of forgetting shit like this.
Quote from: KnightofNi on December 15, 2008, 12:18:19 PM
most of the engineers i know (most of my friends) choose alcoholism as their method of forgetting shit like this.
WORKS FOR ME.
IM AM SO GLAD I AM DONE WITH ALL THAT CRAP
the happiest day of my life was when it was all over I shit you not... calc 1 -4 plus diff equations, but multivariate was the big suck. We never got forumla sheets so I had to memorize EVERYTHING. we weren't allowed to use calculators either, everything had to be done by hand, mind you this was last year and not the 1950s
I feel your pain
It will all be over soon enough, then you can forget most of it, sell your book spend the money on your bike, burn all your notes and piss on the flames like I did.
When the hel lwere you ever allowed to use calculators???? lol It ends with Linear Algebra!! only 1 full year of math to go...
Quote from: KnightofNi on December 15, 2008, 12:18:19 PM
1) what's wrong with being an ME? 2)most of the engineers i know (most of my friends) choose alcoholism as their method of forgetting shit like this.
Nothings wrong with ME, its just that everyone whos sick of every other engineering turns to ME at my school. Its like the default engineering major (they also account for the largest group of engineers out there, ~15% i think, CEs make up the next largest group) so it makes sense. Its a more popular field since MEs are needed for A LOT of things. then CE, then EE then CHEM-E and BIO-E. The last report i read placed CE and ME at relatively high numbers, but ME's were more than half of all Engineers in general. EEs were rising, and Chem-e and bio-e were the least popular.
Anyway, i spoke to the professor about some of the stuff on the test. yea im defintely getting an ~80 on the test, the lost of 20 points were mostly for though process errors and said, he oenst care if i got a 20 on the test, as long as i had ideas on paper that made sense, it was just an excercise to twist the brain and prepare us for the final.
Quote from: He Man on December 14, 2008, 11:27:57 PM
dude is that really you?
Nope, and for the record, that is Schroedinger's equation for the wave function of a particle.
3-D Time-dependent Schrodinger to be precise.
My head hurts.
that was easy. lol
In a twist of irony, my teacher put up that exact equation on the board when he was talking about the diff-q class he teaches. except he used f(x,y) in place of those werid letters that i want no association with. And strange enough it was cause i said, wtf is a gradient squared?? and thought to myself, hey, didnt i type that somewhere. :-\
So im passing all my class with B+ or better. yay......xpt i failed physics miserably, even with a 30pt curve. I dont feel to bad though. only 4 of the 67 students passed. That F really kills my GPA though. since this is my first semester. [bang]
Yikes!
Math.
That which fried my brain more so than anything else in college.
Including beer, drugs and ladies.
Quote from: HobokenHooligan on December 15, 2008, 07:03:11 PM
IM AM SO GLAD I AM DONE WITH ALL THAT CRAP
the happiest day of my life was when it was all over I shit you not... calc 1 -4 plus diff equations, but multivariate was the big suck. We never got forumla sheets so I had to memorize EVERYTHING. we weren't allowed to use calculators either, everything had to be done by hand, mind you this was last year and not the 1950s
I feel your pain
It will all be over soon enough, then you can forget most of it, sell your book spend the money on your bike, burn all your notes and piss on the flames like I did.
holy jebus...was your prof the marquis de sade?
Quote from: He Man on December 15, 2008, 11:09:46 PM
So im passing all my class with B+ or better. yay......xpt i failed physics miserably, even with a 30pt curve. I dont feel to bad though. only 4 of the 67 students passed. That F really kills my GPA though. since this is my first semester. [bang]
How in the hell do you pass high level math, but fail physics??? I always did great in my physics classes, but struggled in the math ones...not practical enough I guess. ???
Which physics?
this is why I went biology instead of ME or the likes.
I use a little statistics and thats all the math I need, besides the basic skills 8)
Quote from: Triple J on December 16, 2008, 09:40:39 AM
How in the hell do you pass high level math, but fail physics??? I always did great in my physics classes, but struggled in the math ones...not practical enough I guess. ???
Which physics?
Simple. 45 mins, 16 questions.
Physics II is a requirement only for engineers, physics, and math majors. 67 students in our section. avg is ~45 first test, 30 second test, and 60 third test(only the good people stayed). He says he only passes about 5-10 people a semester.
Hea terrible professor. Says the test will be like home work questions, but they become some crazy combination of integration to get the numbers just to apply the physics. He has never picked up a piece of chalk. EVER. he does everything by word pad and MS paint.
I passed physics I with an A and skipped the final. It was on the same difficulty as this class, but the prof graded us on the application of physics, not trying to trick us. We had 1:30 to do 4 questions.
The final is departmental, so hopefully it is MUCH easier.....
Do you guys think its possible to do both Diffy-Q and Linear Algebra in 1 semester?
The 2 used to be combined into 1 class at Cal Poly.
Quote from: He Man on December 16, 2008, 12:26:11 PM
Do you guys think its possible to do both Diffy-Q and Linear Algebra in 1 semester?
Lin Alg is pretty easy-much easier than what you're doing, so yes.
Diffy-screws is also not bad. Go for it.
Quote from: He Man on December 16, 2008, 12:26:11 PM
Hea terrible professor. Says the test will be like home work questions, but they become some crazy combination of integration to get the numbers just to apply the physics. He has never picked up a piece of chalk. EVER. he does everything by word pad and MS paint.
I passed physics I with an A and skipped the final. It was on the same difficulty as this class, but the prof graded us on the application of physics, not trying to trick us. We had 1:30 to do 4 questions.
The final is departmental, so hopefully it is MUCH easier.....
Have fun filling out his review! [thumbsup]
Quote from: He Man on December 16, 2008, 12:26:11 PM
Simple. 45 mins, 16 questions.
Physics II is a requirement only for engineers, physics, and math majors. 67 students in our section. avg is ~45 first test, 30 second test, and 60 third test(only the good people stayed). He says he only passes about 5-10 people a semester.
Hea terrible professor. Says the test will be like home work questions, but they become some crazy combination of integration to get the numbers just to apply the physics. He has never picked up a piece of chalk. EVER. he does everything by word pad and MS paint.
I passed physics I with an A and skipped the final. It was on the same difficulty as this class, but the prof graded us on the application of physics, not trying to trick us. We had 1:30 to do 4 questions.
The final is departmental, so hopefully it is MUCH easier.....
Do you guys think its possible to do both Diffy-Q and Linear Algebra in 1 semester?
Physics II is a requirement for a Bio or Chem degree at the school I went to. It just about kicked my ass, but I got a couple good punches in in the last round and took that bastard down [laugh]
Quote from: MrIncredible on December 16, 2008, 12:52:34 PM
Lin Alg is pretty easy-much easier than what you're doing, so yes.
Diffy-screws is also not bad. Go for it.
good to hear, for the EEs at my school, they are scheduled to take it both in 1 semester. Thats 15 credits 5 classes next semester. Ill leave Physics II for summer (ill just take it at the community college thats part of the NY city school system. :p)
as for his review. Anything i say aint gonna do a damn thing. The last Physics II class had a petition to have him stop teaching, even though it had over 300+ signatures, it didnt do a damn thing.....mostly cause hes head of the dept.
Quote from: He Man on December 16, 2008, 02:19:59 PM
good to hear, for the EEs at my school, they are scheduled to take it both in 1 semester. Thats 15 credits 5 classes next semester. Ill leave Physics II for summer (ill just take it at the community college thats part of the NY city school system. :p)
as for his review. Anything i say aint gonna do a damn thing. The last Physics II class had a petition to have him stop teaching, even though it had over 300+ signatures, it didnt do a damn thing.....mostly cause hes head of the dept.
The EEs probably aren't going to delve into it as far. We often had "Bolts for dolts" and "Volts for dolts" for the times when MEs had to take an intro to EE class, and for when the EEs had to take an intro to ME class.
You may be better off taking their version, if the credit is the same. Asking the professor about it may give you a hint.
Schrodinger's = very impressive.
Even if you're not a p-chemist, it's a bit generic... I'd be truly in awe if you used Dirac notation. The Bras and Kets would totally get you chicks!
Quote from: MrIncredible on December 14, 2008, 11:24:04 PM
This is how I roll ;D
(http://img399.imageshack.us/img399/5766/tat004fl2.jpg)
Jesus titty make the beast with two backsing Christ, is that math? (http://s3.amazonaws.com/advrider/eek7.gif)
Great. Just great. Can't wait to start college. (http://s3.amazonaws.com/advrider/bluduh.gif) (http://www.advrider.com/forums/images/smilies/puke.gif)
HEY where did those faces come from? i demand that they be part of the stock set!!!
For the record...
I am happy to help anyone with the higher level math/physics should they need it. Just PM me.
Quote from: He Man on December 16, 2008, 05:40:59 PM
HEY where did those faces come from? i demand that they be part of the stock set!!!
Got 'em from the ADV smiley page. Kind of a PITA to use 'em. Gotta copy image address and them paste it into an img tag. Well worth the effort, imo.