Volumes of Revolution Cross Sections

ChemE14
Thu, 29 Apr 2010 00:05:51 +0000

No, you haven’t been led astray. It’s just easier for ME to derive them (I don’t like memorization too much - for example, on an equilateral triangle I would rather find the height by splitting the thing in two and doing 30-60-90 rule, instead of memorizing A=sqrt(3)/4 * b^2 - don’t ask why). If it’s easier for you to just memorize the equations, then that’s perfectly fine. Some people in my class relied on the equations so much that they forgot the basic concept of the whole thing, and on one problem we worked, the equation for the cross-sectional area was GIVEN (something like A(x) = 4 + 3x/2), but they were lost because they were wondering what shape it was, they didn’t think they had an equation. So as long as you know the basic idea behind the whole thing, then yes, go ahead and memorize it.