Question

If the copper is drawn into wire whose diameter is 6.50 mm, how many feet of copper can be obtained from the ingot? the density of copper is 8.94 g/cm3

Answer 1

Assume that an ingot of copper has a mass of 9.1 kg or 9100 g.

The cross-sectional area of the copper wire with diameter of 6.5 mm (or 0.65 cm) is
A = (π/4)*(0.65 cm)² = 0.3318 cm²

The density of copper is given as 8.94 g/cm³.
If the length of copper wire is L cm, then 
(0.3318 cm²)*(L cm)*(8.94 g/cm³) = 9100 g
L = 9100/(0.3318*8.94) = 3.0678 x 10³ cm

Note that
1 cm = 1/2.54 in = 1/2.54 in = 0.3937 in
        = 0.3937/12 = 0.03281 ft

Therefore
L = (3.0678 x 10³ cm)*(0.03281 ft/cm) = 100.65 ft

Answer: 100.65 ft