Question

A copper sphere of diameter $6m$ is drawn into a wire of diameter $0.4cm$. The length of the wire is

• A. $6m$
• B. $8m$
• C. $9m$
• D. None of these

Answer 1

The correct option is C $9m$

Radius of wire$=\frac{0.4}{2}=0.2cm$
Radius of sphere$=\frac{6}{2}=3m$
Volume of wire (cyl) $=$ Vol of sphere
$\Rightarrow \pi \times {\left(0.2\right)}^2\times h=\frac{4}{3}\times \pi \times 3^3$
$\Rightarrow h=900cm=9m$