# Volume of a cylinder

• Jul 11th 2005, 06:17 PM
ImReddy
Volume of a cylinder
Hello, please help me refresh my memory, I need to figure out how much concrete an eight inch diameter by eight feet tube will hold. I remember the ....3.14 thing, but can't remember how to use it. Thanks!!!
ImReddy :D
• Jul 11th 2005, 09:13 PM
Math Help
Volume of a cylinder
8" diameter x 8'

First find the cross sectional area of the tube which is the area of the circle with 8" diameter and then multiply that area by the length of the tube.

The formula for the volume of a cylinder is $V = \pi*r^2*L$

so $V = \pi*(4in)^2*8ft$

lets convert everything to inches before we work it out

$V = \pi*(4in)^2*(8*12in)$

$V = \pi*16in^2*96in$

$\pi*1536in^3$

or roughly 4825.5 in^3 of cement

check out the google conversion tool