# cylinder volume

Discussion in 'Math' started by adamclark, Dec 2, 2013.

Oct 4, 2013
472
6
Whats the formula for measuring the volume in cf of a cylinder?

2. ### MikeML AAC Fanatic!

Oct 2, 2009
5,451
1,071
Area of the base time height. Units in feet.

3. ### tracecom AAC Fanatic!

Apr 16, 2010
3,925
1,424
volume of a cylinder = pi times radius squared times height

Last edited: Dec 4, 2013

Oct 4, 2013
472
6
Im building a woofer box for my car and I have some 12 inch abs pipe. It measures 11 inches i.d. . I need 1.25 cf of air for my woofer. How long would it need to be? I understand your formula ok but how would I find the length it needs to be?

5. ### Wendy Moderator

Mar 24, 2008
21,012
2,744
11" = 5.5" radius = 0.458'
3.1416 X .458'² X L = 1.25'³
1.439' L = 1.25'³
L = 1.897' or 22.76"

The volume of 2' long pipe at 11" width is.

CF = π R² L = 3.1416 X 5.5"² X 24" = 2280.80"³ or 1.32'³

Be aware though, with any tube of air comes resonance.

Last edited: Dec 3, 2013
6. ### WBahn Moderator

Mar 31, 2012
20,223
5,747
I think you meant "volume" of a cylinder.

7. ### WBahn Moderator

Mar 31, 2012
20,223
5,747
Bill, look at your notation. If 5.5"² means to square 5.5" and not 5.5 square inches, then doesn't 2280.80"³ have to mean to cube 2280.80" and not 2280.80" cubic inches?

Might I suggest:

CF = π R² L = 3.1416 X (5.5")² X 24" = (2280.80)"³ or (1.32)'³

or

CF = π R² L = 3.1416 X (5.5")² X 24" = 2280.80("³) or 1.32('³)

Probably the best would be to not use the " and ', despite how convenient they are.

CF = π R² L = 3.1416 X (5.5 in)² X 24 in = 2280.80 in³ or 1.32 ft³

Last edited: Dec 4, 2013
8. ### Wendy Moderator

Mar 24, 2008
21,012
2,744
Picky! At least I used notations!

9. ### tracecom AAC Fanatic!

Apr 16, 2010
3,925
1,424
Hey, I got the right answer; I just forgot the question.