linear feet to cubic yards

I need to convert 221 linear feet of concrete into cubic yards, but I have a 18' X 8" in dia. pipe inside the concrete the thickness of the concrete is 2' 9" in thickness.........Please help!!!!!!!!

[gubment_cheez]

you have to calculate the volume of the concrete, then subtract the volume of the pipe that is inside the volume of concrete
to calculate the volume, you multiply the width, by the depth, by the height
and to get the volume of the pipe you do ((((diameter/2)^2)*pi[3.1415926535897932384626433832795])*length. if the pipe is only partially submerged in the concrete, then the calculation would be different, more complex

[Robert Fogt]

Can you provide a bit more information? If I understand you correctly, you would do something like this:

linear feet * width in feet * thickness in feet = cubic feet

Now you will need to subtract the volume of the pipe.
18 feet * (Pi * (4/12) * (4/12)) = 6.28 cubic feet

cubic feet of cement - 6.28 cubic feet = total cubic feet

[Robert Fogt]

I guess I just type too much slower than gubment_cheez.

[gubment_cheez]

Originally Posted by Robert Fogt

I guess I just type too much slower than gubment_cheez.

which is why I am campaigning to take over the site. . I will make tax cuts across the board, and give more funding to health, and welfare.
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that all men are created equal, and unique.
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Originally Posted by Robert Fogt

Can you provide a bit more information? If I understand you correctly, you would do something like this:

linear feet * width in feet * thickness in feet = cubic feet

Now you will need to subtract the volume of the pipe.
18 feet * (Pi * (4/12) * (4/12)) = 6.28 cubic feet

cubic feet of cement - 6.28 cubic feet = total cubic feet

I still don't understand.......what is Pi and why (4/12) what does this mean?

[Robert Fogt]

Originally Posted by glo

I still don't understand.......what is Pi and why (4/12) what does this mean?

Pi is a mathmatical concept, it is the relationship of a circles radius to its circumference. It is a number equal to about 3.14, or some calculators give more accuracy up to about 3.1415926535897932384626433832795

4 is inches, and 4/12 is a quick way to convert it to feet. Since all units need to be the same, for example cant multiply feet by inches, only feet by feet.

4 inches / 12 = 4/12 = 0.333 feet
18 feet * (3.14 * 0.333 feet * 0.333 feet) = 6.28 cubic feet

But that is only the volume of the pipe. You subtract that volume from the volume of the cement, and you cant calculate that until you know the width.