Help me with this math problem

[Guest]

Hi everyone, help me with this math problem

A piece of copper is 4 in. in length, 2 in. in width, and 1/2 in. thick is formed into a wire 100 yds. in length and uniform thickness. Find diameter of wire.

Volume of copper = 4 * 2 * .5 = 4 cu. in.

Length of wire = 100 * 3 * 12 = 3600 in.

Wire is a cylinder: Volume of cylinder = pi * r^2 * height or length.

3.1416 * r^2 * 3600 = 4

11309.76 * r^2 = 4

Not sure how to proceed - Where am I incorrect?

[romsek]

as you noted the volume stays constant

[tex]V = 4 =\pi r^2 \ell = 3600 \pi r^2\\~\\

r^2 = \dfrac{4}{3600 \pi} = \dfrac{1}{900 \pi}\\~\\

r = \sqrt{\dfrac{1}{900\pi}} = \dfrac{1}{30\sqrt{\pi}}\\~\\

D = 2r = \dfrac{2}{30\sqrt{\pi}}[/tex]