Math CentralQuandaries & Queries


Question from christian, a student:

how many cubic feet are in a pipe that is 3" (inside diameter) and 459 feet long?


A pipe is a cylinder and the volume of the cylinder is equal to its cross-sectional area (the area of the circle) multiplied by the length.

So convert 3" to 0.25 feet, then take half of that as the radius of the pipe in feet: 0.125.

Now calculate the volume in cubic feet: V = (pi) r2 d, where r is the radius, d is the length of the pipe, and pi is about 3.14159.

Stephen La Rocque.

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