Cubic feet

Having trouble finding formula for converting a cylinder to cubic feet. How many cubic feet in a cylinder 10" in diameter and 8' long. Trying to figure out how many cubic feet of lumber in a log. Thanks.
Vic
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Should be something like ((10/12)/2)**2*pi*8
In other words 1/2 the diameter squared, times pi, times length. Use 10/12 to convert diameter inches into feet.
Bill Ranck Blacksburg, Va.
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meldingsnyheter: snipped-for-privacy@4ax.com...

Formula: r x r x 3,14 x h, which in this case means: 5 x 5 x 3,14 x 8 = 628 cubic inches. cubic inches to cubic feet? Im european, so that beats me:-)
Bjarte
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Ummh. . .slight miscalculation there, Bjarte. One needs to convert all the measurements to the same unit. You multiplied the radius as measured in inches but height as measured in feet. The 8 feet needs to be converted to 96 inches (8 X 12). Following your formula, it shoud be:
5 X 5 X 3.14 X 96u36 cubic inches
A cubic foot is 1728 cubic inches (12 X 12 X 12). Therefore, 7536 c.i. = 4.36 c.f.
Thus, a log 10" in diameter (5" radius) and 8' (or 96") long would have a volume of about 4 1/3 cubic feet.
Ian

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1 cubic foot = 1728 cubic inches
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1728 cubic inches = 1 cubic foot
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To conver from cubic inches to cubic feet simply divide by 144 (12^2) 628 / 144 = 4.361
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I_ snipped-for-privacy@hotmail.com says...

is flawed in that the length should have been x12 for cubic inches. The log is 8 feet long I assume ?
As 1 cubic foot is 12x12x12 inches, you would need to divide by 12^3 1728 to convert cubic inches to cubic feet.
Cheers Ray
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Doh! Stupid me...divide by 12^3 or 1728...628/1728 = .3634 cf
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I_ snipped-for-privacy@hotmail.com (SpazMaTaz) wrote:

Yeah, except that it's 8 _feet_ long, not 8 _inches_. Calculation above should have been 5 x 5 x 3.14 x 8 x 12 = 7536 cubic inches Divided by 1728 cu in / cu ft = 4.36 cu ft.
-- Doug Miller (alphageek at milmac dot com)
How come we choose from just two people to run for president and 50 for Miss America?
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V = (pi)r^2 x h
Where h is the height.
Convert your measurement to inches, apply the above formula, then divide by 1728 cubic inches to get the cubic feet.
--
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Last update: 9/21/03
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brought forth from the murky depths:

http://www.google.com/search?q=board+foot+calculator Use one of the sites they provide and input your numbers to get board feet. Divide that number by 12 for cubic feet.
----------------------------------------------------------------- When I die, I'm leaving my body to science fiction. --Steven Wright ---------------------------- http://diversify.com Comprehensive Website Development
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brought forth from the murky depths:

Knowing that I should have steered you to the lumber calc brought me back again with more.
Basic answer: http://www.thermalinc.com/math/roundtank.htm 6.67cu/ft
Real answer from lumber calc: http://www.woodweb.com/cgi-bin/calculators/calc.pl?calculator=log_volume Takes log taper/waste into account. 18 or 30bf, 1.5 or 2.5cu/ft.
----------------------------------------------------------------- When I die, I'm leaving my body to science fiction. --Steven Wright ---------------------------- http://diversify.com Comprehensive Website Development
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For a circular cylinder, Pi*r^2*h
For a general cylinder, (base area)*height. It need not be a right cylinder.
The top and bottom need not be round, but they must be the same shape and parallel.
The sides need not be perpendicular to the top, but they must be straight and parallel.
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Victor wrote:

Wow, a math question I can actually answer off the top of my head. Amazing. I guess I'll always remember that pie are square.
Since it has already been answered in spades, I will interject a smartass comment instead.
If you have cubic feet, you need to buy some shoes that aren't so tight.
--
Michael McIntyre ---- Silvan < snipped-for-privacy@users.sourceforge.net>
Linux fanatic, and certified Geek; registered Linux user #243621
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On Fri, 12 Dec 2003 18:03:44 -0500, Silvan

No, pie are round. It is corn bread that you were thinking of...
HTH,
--
Kenneth

If you email... Please remove the "SPAMLESS."
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Kenneth wrote:

Tell that to SWMBO. She makes square pies and round cornbread.
--
Michael McIntyre ---- Silvan < snipped-for-privacy@users.sourceforge.net>
Linux fanatic, and certified Geek; registered Linux user #243621
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A = Pi * radius squared. Radius = diameter / 2 = 10" / 2 = 5" A = Pi * (5" * 5") -- but this will give area in square inches. Convert to feet: A = Pi * (5/12' * 5/12') A = 3.14 * (0.4167 * 0.4167) A = 0.545 square feet
V = A * 8' V = 0.545 * 8 V = 4.36 cubic feet
-- Doug Miller (alphageek at milmac dot com)
How come we choose from just two people to run for president and 50 for Miss America?
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wrote:

1 cubic foot = 12^3 = 1728 cu inches
volume of a right cylinder = (pi * r^2) * h r = 5 inches (radius of the base) h = 8 * 12 = 96 inches (altitude or height of the cylinder)
plugging into formula... = (3.14159 * 5^2) * 96 = 7539 cu inches = 4.36 cu ft (approx.)
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pi X r squared X height

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