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A copper pipe, used for plumbing from the water main to a house, is $3$ meters long and has a circular cross-section $2.8 cm$ in diameter. There is a $2 cm$ diameter hole in the center of the cross-section for the entire length of the rod. What is the volume of copper in the rod in cubic inches? The density of copper is $559 \large \frac{lbm}{(ft)^{3}}$. What is the mass of the copper pipe in pounds?

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1 Answer 1

Hint: The volume of a cylinder of radius $r$ and height $h$ is $\pi r^2 h$. You have one cylinder with a cylindrical hole in it, so subtract the volume of the hole from the outer cylinder. Then for the mass, you need to watch the units.

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