# An alloy has a density of #rho=8.900xx10^3*kg*m^-3#...can you address the following question?

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What would be the mass of a #1.5*m# length of a pipe made from this alloy if its OUTER radius was #1.75xx10^-2*m# , and the BORE of the pipe, its inner radius, was #1.25xx10^-2*m# ?

What would be the mass of a

##### 1 Answer

Approx......

#### Explanation:

We work out (i) the mass of a solid pipe......

i.e.

And (ii) we work the mass of an inner pipe, i.e. the mass that an internal pipe would have......

And the mass of the given pipe is simply

Note that it might help you to draw a diagram showing the cross-section of the pipe, and the areas of the two cross-sections we need. Good luck.

Note that in plumbing, when we talk of say