Question

The diameter of a sphere is 6 cm. It is melted and drawn into a wire of diameter 2 mm. The length of the wire is
(a) 12 m
(b) 18 m
(c) 36 m
(d) 66 m

Answer 1

(c) 36 m
Let h m be the length of the wire.
Volume of the sphere = volume of the wire
$$\begin{gathered} \Rightarrow \frac{4}{3}\mathrm{\pi }\times 3^3=\mathrm{\pi }\times {\left(0.1\right)}^2\times h \\ \Rightarrow h=\frac{4\times 9}{0.001} \\ =3600\mathrm{cm} \\ =36\mathrm{m} \end{gathered}$$