Chemisty
posted by love on .
Wire is often sold in pounds spools according to the wire guage number. That number refers to the diameter of the wire. How many meters are in 3Ib spool of 12 gauge aluminum wire? A 12guage wire has a diameter of 0.0808 in. Aluminum has a density of 2.70 g/cm^3. (V=3.14r^2L)

I would change 0.0808 inches to cm and 3 pounds to grams. 2.54 cm = 1 inch and 453.6 g/lb, then 0.0808 in x (2.54 cm/in) = ?
and 3 pounds x (453.6 g/lb)= ?
The area of the wire is pi*r^2.
Volume = pi*r^2*length of wire
So if you know volume, pi, and r you can calculate length. Volume = mass/density = mass (grams)/density.
Solve for length in cm and convert to m 
so i would 0.0808 in x (2.54 cm/in) = 2.6E1
3 pounds x (453.6 g/lb)= 1.4E3
SO THAN WHAT DO I DO NEXT 
0.0808 2.54 is not 0.26 and you shouldn't round to two places. You are allowed 3. My calculator reads about 0.205 cm. That's the diameter so take half of that to arrive at the radius. You've rounded 453.6 x 3 too much. I would keep it as 1360.8 grams. You can round later.
Next you calculate volume.
Volume = mass/density = 1360.8/2.70 = ?
Then V = pi*r^2*length
V from above.
pi = 3.14
r from above and square it.
Length. Solve for this.