realchill127

Find the mass and center of mass of the solid E bounded by the parabolic cylinder z = 1 - y^2 and the planes x + z =1, x = 0, and z = 0 with the density function p(x,y,z) = 4.

I really seem to struggle with figuring out how to set up these triple integrals. I know these equations.

m = ∫∫∫[over D] p(x,y,z)dA

x[center] = 1/m ∫∫∫[over D] x*p(x,y,z)dA

y[center] = 1/m ∫∫∫[over D] y*p(x,y,z)dA

I just dont know how to set the domain. I could convert to cylindrical coordinates, but then I have three functions of z: z = 1 - (rsin(θ))^2 ; rcos(θ) + z = 1 ; z = 0. I know that θ will be from 0 to 2pi, but I dont know how to choose what z will be from and what r will be from. I appreciate any help!

I am unsure how to solve this problem. Use a triple integral to find the volume of the solid enclosed by the cylinder x^2 + z^2 = 4 and the planes y = -1 and y+z=4.

I just cant really figure out how to set up the integral. Please explain to me how to approach this problem, not just the answer. Thank you for any help!

So I am just not getting this. Why does ln(1-e^x) - ln(1-e) simplify to ln((e^x -1)/(e-1))

and not ln((1-e^x)/(1-e))

My professor said that he could ask for y' after solving an exact differential equation, but never went over it in class -.-. So example:

[e^(2y) - ycos(xy)]dx + [2xe^(2y) - xcos(xy) + 2y]dy = 0

This comes out that the general solution is: C = xe^(2y) -sin(xy) + y^2. You can check me, but I am positive I did this right. So how can I obtain y' from this. I don't really understand this general solution either...please help if you can. Thank you.

I posted this before and got a question. I don't really understand what the solution means although I can methodically work it out. I know I just multiply by dy/dx to find y', but how can I explicitly solve for y'?

My professor said that he could ask for y' after solving an exact differential equation, but never went over it in class -.-. So example:

[e^(2y) - ycos(xy)]dx + [2xe^(2y) - xcos(xy) + 2y]dy = 0

This comes out that the general solution is: C = xe^(2y) -sin(xy) + y^2. You can check me, but I am positive I did this right. So how can I obtain y' from this. I don't really understand this general solution either...please help if you can. Thank you.

I am having a really rough time with these two dimensional limit problems.

lim 5x^2y/(x^2 + y^2)

(x,y)->(0,0)

I found the limit to be 0 by using y = mx which gave me 0 and y = 0 gave me 0 so does this mean the limit is 0? I don't understand this at all.

Determine the set of points at which f(x,y) is continuous (e^(-xy)) / (sqr(5-y))

This one I don't really know where to start.

Please help, I am not looking for the answers so much as to how to solve them. Thank you.

I am doing a spanish assignment that requires I interview two people and have them answer this question:

¿Qué hacía tu mamá o papá cuando él o ella tenía cinco años?

If you can help great! Thank you in advance. Also, this question confuses me...is it saying what did your mom or dad do when he or she was five. If this is the case I believe he or she is referring to the interviewee.

I just downloaded and installed Ubuntu but I cannot do anything because I have no created user. If there was a default one made I don't know the username and password.

Is there anything I can do to create a super user account while on guest? What should I do?

Thanks!

Well, could I? How complicated would it be.

I am about to graduate from high school and pursue my physics degree! Please help clear up these questions I have :)

Ok so I know about spectroscopy and how electromagnetic radiation causes electrons to gain more energy and move to a more excited state...emission absorption spectrums yada yada. I have a couple of questions however.

What makes an electron lose the energy it gains from the electromagnetic radiation? Why must it emit the photons and not simply just stay in the excited state? Is it an entropy problem or does it lose a certain amount of kinetic energy and the rest of the "gap" between energy levels is emitted out. That leads to my second question.

Do electrons emit the same radiation as it absorbed when it goes down the subsequent energy level? If so, doesn't that categorize it as a black-body?

Is thermodynamic entropy simply a mathematical problem...like statistical...or is there a physical reason for it? I apologize if that doesn't make much sense. In essence...why does entropy occur? I would assume it would just be math related to the statistics of a system...or maybe im totally off.

Tell me about it

Perhaps the science section isnt quite appropriate due to the lack of experimental proof that can be shown, but this is where i will most likely get serious intelligent answers. So to the question, do you think we live in a Universe or a Multiverse. Why?

Ok so say there was this guy named John. John was a really good guy, Christian, helped everyone etc. etc. One day John got hit by a car. Suffering from brain damage he is now angry, Atheist, and a totally different person with different memories and experiences. But this is not his choice, the personality section of his brain was severely damaged. Now we have two John's, the first and the second. Who is judged by the Christian God?

Well i was just reading a bit and found several people saying Muhammad was a fraud. Never heard this before. Anybody got the information, thanks

Hey everyone, basically tell me what you think. Would corruption and evil take over or will people still have good ethics. Higher suicide rate? More homicide? More drugs? But then again you have less deaths by religion. I think we would be about the same. I think we would find something else to bicker about and kill ourselves over.

Thoughts Below.

Well im an atheist, and i dislike Christians simply for their general likeness to be ignorant. I do not however have a strong and similar dislike for other religions like Hinduism. I think this is because there is much less projections of their beliefs on me. Any of you feel the same dislike for Christians but not for other religions? Want to rant about something? Do you have any theories to why most atheists dislike Christians more, or personal reasons?

Anyway, thoughts below, thanks.

Go ahead you crazy people and post your unrelated bible verse, but for you sane people out there have you ever noticed this? I was recently driving down a highway when i saw, seriously, a sign that said "Jesus IS God." Since when is Jesus the new ruler, and since when is he God? I dont know tons about the religion, im anti-religious, but Jesus seriously seems to have become the new face of Christianity instead of that one person who supposedly created everything, including Jesus.....umm oh yeah God.

Leave your thoughts below. (Or your silly bible verse)

I dont get this, when people talk about how amazing heaven is they always associate it with gold and some sort of expensive thing holding monetary value. Just seems a bit shallow and greedy if you ask me. Tell me what you think.

Well my class puts up quotes and im wondering what some of you guys would put up there. It has to be original and preferably intellectual. Post it up.

For the record mine would be: Upon the back of love lies the heaviest of sorrows

Ok so idk why but today ive just been cranking out poems. Ive never really written all that much before but idk it seems to be working for me today. So ive posted the critic links to the poems ive written, tell me what you think i should work on and if i could sell a poem book or something. keep in mind all of these were done in 2-8 min and were unedited, which wouldnt be the case if i was publishing.

http://answers.yahoo.com/question/index;_ylt=AhkUu...

http://answers.yahoo.com/question/index;_ylt=AuM1m...

http://answers.yahoo.com/question/index;_ylt=Aipfn...

Oh and i dont expect you to read all of them, just skim er something you lazy fools lol