soconfused Posted September 23, 2004 Posted September 23, 2004 hello guys! i have a column with a shape of a cylinder. the radius is 2cm and the heigh is 5cm. i have to calculate the cross-sectional area of the column. i wonder what is the formula and how is the calculation? it has been a long time since i last had my math lectures, so i really hope for some help! thanks alot!
5614 Posted September 23, 2004 Posted September 23, 2004 volume of a cylinder: [i cant do maths symbols, i dont know how, im not into maths that much and have neva learnt how so...] volume of a cylinder: pir^2h or pi X radius-squared X height. so when r = 2 and h = 5 volume = pi X 2^2 X 5 volume = pi X 4 X 5 volume = pi X 20 volume = 62.83185 [to 5 D.P] is that what you wanted?
Cap'n Refsmmat Posted September 23, 2004 Posted September 23, 2004 You're not supposed to do it all for him.
5614 Posted September 23, 2004 Posted September 23, 2004 but i couldnt do all the pi stuff and ^2 in proper mathematical symbols, i thought he'd get confused, once he's got the formulae, anyone can use a calculator and replace r with 2 etc! anyway, he's a new memeber, lets me nice to him at first! how do you do all the maths symbols?
soconfused Posted September 23, 2004 Author Posted September 23, 2004 hi guys! thanks for sharing, but i don't think we are right, since the answer must be in cm^2, which means it is not the volume of the column we are looking for. by the way what does it mean with cross-sectional area? is that the areal of the column? yeah! and thanks for being nice to me due to my first visit here
Dave Posted September 23, 2004 Posted September 23, 2004 thanks for sharing, but i don't think we are right, since the answer must be in cm^2, which means it is not the volume of the column we are looking for. by the way what does it mean with cross-sectional area? is that the areal of the column? Nope. You have: [math]V = \pi r^2 h[/math], since r2 is measured in cm2 and h in cm, you have cm3, which is a volume.
Dave Posted September 23, 2004 Posted September 23, 2004 how do you do all the maths symbols? Use [math] tags.
soconfused Posted September 23, 2004 Author Posted September 23, 2004 hi Dave! are you sure that cross-sectional area is the same like the areal of the column?
Dave Posted September 23, 2004 Posted September 23, 2004 That's not cross sectional area. I apologise, I should've used V= instead of A= for that formula [math]A = \pi r^2[/math] [math]V = \pi r^2 h[/math].
soconfused Posted September 23, 2004 Author Posted September 23, 2004 so what is cross-sectional area?
Woxor Posted September 24, 2004 Posted September 24, 2004 by the way what does it mean with cross-sectional area? is that the areal of the column? Assuming you're not supposed to take the cross-section "long-ways" (i.e. splitting it down the middle like string cheese), the cross-sectional area is the area of a slice through the object. Since I can't think of a better way to describe it, the yellow circle in this picture is a cross-section. The area of the circle is the cross-sectional area.
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