# Copper Wire

• Apr 25th 2010, 08:28 PM
BrendanLoftus
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.
• Apr 25th 2010, 10:56 PM
earboth
Quote:

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 '
• Apr 26th 2010, 06:12 PM
BrendanLoftus
Good thats what I ended up getting, thanks so much!