Anyone have any ideas?

[Gamingphreek]

In Second Semester Calc we are doing Volumes of Cylindrical shells. I can sort of see what they want me to do but I can't quite grasp the concept. In some cases I can't even see how I'm supposed to make my graph "3-D".

Does anyone have know of any easily accessible resources they may have used to learn this. I'll go to my professor, but I want to make sure that I can't do it first.

-Kevin

 

[WildHorse]

If you read your way through this it'll help in general:
the best Calc Primer I've seen

 

[Tylanner]

here

 

[Gamingphreek]

Thanks both of you! Differentiation and Integration in their own respect are easy. I more need help on the solids of revolution and stuff- these are great links.

I'll definitely read through both of them and try to get a little better before I go pester the professor (I don't like asking for help like that)

-Kevin

 

[WildHorse]

Originally posted by: Gamingphreek

< cut >
. . . before I go pester the professor (I don't like asking for help like that)

-Kevin

Well it's suggested that you change your thinking on that.

Actually, asking the prof for help is a great way to get to know him/her a little bit. The objective of that is to position yourself for later on, when you want to ask him/her to write you a letter of recommendation.

Do reach out a little bit & initiate contacts.

 

[chuckywang]

Ask me. I can help.

 

[futuristicmonkey]

Originally posted by: Gamingphreek
Thanks both of you! Differentiation and Integration in their own respect are easy. I more need help on the solids of revolution and stuff- these are great links.

I'll definitely read through both of them and try to get a little better before I go pester the professor (I don't like asking for help like that)

-Kevin

We're doing the same thing right now. Basically, think of each cylinder's shell as having an arbitrarily small volume, tho it does have one. The narrower you make each cylinder's shell the more you can fit into the solid you're measuring, which provides a 'higher' (actually, infinite) resolution. When you take the integral of the SA of the shells on the interval, the shell's change according to the SA's height 'f(x)' and the radius of the shell (in general cases, only 'x') and you 'add up' the infinite amount of shells.

Hope this helps.

-ben

 

[Gamingphreek]

Thanks guys.

Well the reason I said that I don't want to "pester the professor" is because I am not used to asking for help. Normally things came to me the minute I saw them in HS...in College though they aren't quite going that smoothly. While I get A's on most of my quizzes and HW's my tests are HORRID. I try to stick to studying/asking friends for help in college- I have only gone to the professor once (Last semester). I should really change that I guess :-

I actually got my friend to explain it and it sounds almost too easy.

Since I have 2 equations- One for the outer shell, one for the inner shell- I am merely supposed to graph them, figure out which one is "on top" or the "outer" function. Then subtract it by the inner function. After that I merely integrate over the selected integral it and multiply it by 2[pi]. Is that right or am I simplifying this way way too much.

-Kevin

Edit: Thank you so much for the help though. I really appreciate it!

 

[Crono]

Originally posted by: Gamingphreek
Thanks guys.

Well the reason I said that I don't want to "pester the professor" is because I am not used to asking for help. Normally things came to me the minute I saw them in HS...in College though they aren't quite going that smoothly. While I get A's on most of my quizzes and HW's my tests are HORRID. I try to stick to studying/asking friends for help in college- I have only gone to the professor once (Last semester). I should really change that I guess :-

I actually got my friend to explain it and it sounds almost too easy.

Since I have 2 equations- One for the outer shell, one for the inner shell- I am merely supposed to graph them, figure out which one is "on top" or the "outer" function. Then subtract it by the inner function. After that I merely integrate over the selected integral it and multiply it by 2[pi]. Is that right or am I simplifying this way way too much.

-Kevin

Edit: Thank you so much for the help though. I really appreciate it!

No, that sounds about right. Granted, I'm also in second semester of Calculus right now Just finished the disk and shell methods and we're doing integration with natural logs now. I also don't like asking professor's for help, usually because (even if the professor is good) it takes longer for me to grasp the explanation than if I try to figure it out myself or during a study session with a friend.