How does Volume of Revolution & Integration work?

Discussion in 'General Discussions' started by sprite, Sep 10, 2007.

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  1. sprite

    sprite Newbie

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    We've been learning this at school lately. I can work with the formulas and get the answers, but I'm completely lost as to why it actually works o.o;

    We're in a rush (end of year exams in about 1 month), so our teacher isn't explaining - she just wants to get through the material we have to cover :(.

    Soo, anyone care to explain? (and also, should i take A-level Maths with Mechanics or Stats?)
     
  2. Commy

    Commy Moderator
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    Not sure if i can help you with Volume of revolution, are you talking about revolving something vertically or horizontally along its axis?
    And what part of integration don't you understand? I could probably help you a lot more in that, because i've done that in high school and uni.
    If your teacher isn't explaining it, you might want to stay after class to clarify what you don't understand, or even ask during class. You've probably heard this before, but chances are that the other people are lost too.
    As for subject choices, it depends on what you want to do in the future. In Australia, we call the subjects different things, even in each state. So it would be hard for people from other countries to give you advice on what subject to pick. Even with statistics, that can differ a lot. The subject is broad.

    A level maths with mechanics, sounds like things to do with engineering? I'm not too sure, I couldn't give you advice on that.
    As for stats, i'm doing that in uni. You should have done a little bit of stats in your previous maths subjects, (there's a bit of probability in stats) so if you enjoy it, I'd suggest doing it. Because (in Australia, and i'm assuming in NZ) there's a demand for statisticians, and generally they get paid well. If you're a gun at doing work, and you like commerce subjects, you could do actuarial subjects, which is stats in commerce. But that's really hard, but pays excellently.
    Also, in stats you need to know quite a bit of maths. In the later years, you use differentiation, integration, among other things. But I don't know what things they'll teach in your stats. Could be..binomial and hypergeometric distribution.
    Totally up to you of course. Good luck Kiwi
    By the way, have you seen Black Sheep? It looks pretty hilarious
     
  3. sprite

    sprite Newbie

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    yes, revolving a 2d object around a point to create a 3d shape ^^;
    And as for asking the teacher, she doesn't seem to like me much :S, lol.

    I can work with (what we've learned so far) of integration, but I don't understand why it works. A few links to websites or an explanation would be very much appreciated.

    Thanks for your info on stats. I think i might do mechanics instead, because stats seems very demanding, and I'm not a big fan of probability - it makes my head hurt :|

    Nup, it seems rather wierd o.o; a horror/comedy movie about evil sheep? Only in New Zealand, lol
     
  4. Commy

    Commy Moderator
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    http://en.wikipedia.org/wiki/Integral
    Well, you might want to read the first few parts of that site.The explanations can get pretty complicated further down so this one's probably more suitable.
    http://www.dcu.ie/mathtutor/integration/Main.html#
    It's probably best to just read the summary text on which part of integration you want to understand. Maybe reading your text book might help??
    If you're feeling lazy,
    http://integrals.wolfram.com/index.jsp
    this website will do your integrals for you. It should be fine for the equations at your level. Just read the instructions on how to type them in.
    I mean, even if your teacher doesn't like you, it's her/his duty to help you! If not, just ask a smarter friend, or even another maths teacher. If your school has more than one. Which it probably has.

    Can't really help you with revolution, I did that too long ago to remember how to do it properly.
    Good luck with exams
     
  5. sprite

    sprite Newbie

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    Thanks :). I think i'll do my integrals by hand though, its good practice ^^
     
  6. pspredatorx

    pspredatorx Newbie

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    o_O I did this in grade 11.

    But I don't remember. I remember squaring something. :) Know integration, and that you multiply everything by pi as well.
     
  7. jvjanisse

    jvjanisse Level I

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    well, think of it this way; if you cut a very thin slice of the object (the integration of delta x) you basically have a 1D line (with a height of y); when you revolve the line around its point you have a circle; you do this constantly throughout the line f(x) to get the volume of revolution of the that function from a to b. *if you still need help with this just shoot me a private message and i can help explain when i'm more awake and have a book.*
     
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