Question

The diameter of a metallic sphere is $18$cm. It is melted and drawn into a wire having diameter of cross section $0.4$cm. Find the length of the wire.

Answer 1

Volume of sphere $=$ Volume of wire

$\Rightarrow \frac{4}{3}\pi r_1^3=\pi r_2^{2}h=\frac{4}{3}\times 9^3={\left(0.2\right)}^2\times h\Rightarrow h=\frac{4\times 9\times 9\times 9}{0.04\times 3}$

$h=24300$ cm. Hence, length of wire is $24300$ cm or $243$ m.