Melting Copper Wire to Sphere

Wire is cylindrical with length $h = 243\text{ m} = 24300\text{ cm}$ and radius $r = 2\text{ mm} = 0.2\text{ cm} = \frac{2}{10}\text{ cm}$. Volume of cylindrical wire $= \pi r^2 h = \pi \left(\frac{2}{10}\right)^2 \times 24300 = 972\pi\text{ cm}^3$. Volume of sphere $= \frac{4}{3}\pi R^3 = 972\pi$. $R^3 = 972 \times \frac{3}{4} = 729 \implies R = 9\text{ cm}$. Diameter $= 2R = 18\text{ cm}$.