document.write( "Question 957805: An iron pipe 10 ft. long has an internal diameter of 1 ft. If the iron is 1/2 in. thick, find the volume of metal in the pipe.
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Algebra.Com's Answer #585361 by jsmallt9(3758)\"\" \"About 
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Since the metal of the pipe forms a tube and since it is unlikely you have a formula for the volume of a tube, we must find the volume of the tube by adding or subtracting volumes we can find.\r
\n" ); document.write( "\n" ); document.write( "The pipe, with the air inside of it, forms a cylinder. Just the air inside the pipe also forms a cylinder. And there is a well-known formula for the volume of a cylinder:
\n" ); document.write( "\"V+=+pi%2Ar%5E2%2Ah\"
\n" ); document.write( "The volume of the metal in the pipe, the tube, will be the volume of the pipe and the air minus the volume of the air.

\n" ); document.write( "Now we just need to find the values for the volume formula: the radius and hieght of each cylinder. The internal diameter of the pipe is 1 foot. This makes the radius of the air 1/2 feet. The thickness of the pipe is 1/2 inch or 1/24 foot. This makes the radius of the pipe-and-air cylinder:
\n" ); document.write( "\"1%2F2+%2B+1%2F24+=+12%2F24+%2B+1%2F24+=+13%2F24\" feet. The height of both cylinders is 10 feet.

\n" ); document.write( "Now we can indert these values into our volume formula. For the pipe-and-air cylinder:
\n" ); document.write( "\"V+=+pi%2A%2813%2F24%29%5E2%2A10+=+pi%2A%28169%2F576%29%2A10+=+%28845%2F288%29pi\" cu. ft.

\n" ); document.write( "For the air-only cylinder:
\n" ); document.write( "\"V+=+pi%2A%281%2F2%29%5E2%2A10+=+pi%2A%281%2F4%29%2A10+=+%285%2F2%29pi\" cu. ft.

\n" ); document.write( "For the volume of the metal of the pipe we subtract these:
\n" ); document.write( "\"V+=+%28845%2F288%29pi+-+%285%2F2%29pi\" cu. ft.
\n" ); document.write( "\"V+=+%28845%2F288%29pi+-+%28720%2F288%29pi\" cu. ft.
\n" ); document.write( "\"V+=+%28125%2F288%29pi\" cu. ft.
\n" ); document.write( "This is an exact expression for the volume of the metal of the pipe.
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