A solid copper sphere of radius 9 cm. is melted and reformed into a wire of radius 1 mm. What will be the length of this wire? $left( ight.$ Take $left.pi=frac{22}{7} ight)$

Volume of solid sphere

$=frac{4}{3} pi r^{3}=frac{4}{3} pi imes 9 imes 9 imes 9$

= 972 Scubic cm.

If the length of wire be h cm. then

Volume of wire = 972S

$Rightarrow pileft(frac{1}{10} ight)^{2} h=972 pi$

⇒ h = 97200 cm.= 972 metre