# Math Help - Copper Wire

1. ## Copper Wire

How many feet of copper wire 1/8 inches in diameter can be made from 1 cu. ft. of copper?

given; pi=3.14; 1 cu. ft.= 7.5 gallons; 1 gal= 231 cu. inches

I figured 1 cu. ft.=1732.5 cu.in.

Any help would be greatly appreciated.

2. Originally Posted by BrendanLoftus
How many feet of copper wire 1/8 inches in diameter can be made from 1 cu. ft. of copper?

given; pi=3.14; 1 cu. ft.= 7.5 gallons; 1 gal= 231 cu. inches

I figured 1 cu. ft.=1732.5 cu.in.

Any help would be greatly appreciated.
1. Consider the wire as a circular cylinder with $d=\frac18 ''$ and the length l.

2. The volume of the wire is calculated by

$V_w=\underbrace{\frac14 \cdot \pi \cdot d^2}_{\text{area of cross-section}} \cdot l$

The value of the volume is known to you.

3. Plug in all known values (d, V) and solve for l. The unit of the result is inch. Therefore you have to convert the result into foot.
Spoiler:
I've got l = 11,770.7 '

3. Good thats what I ended up getting, thanks so much!