Question

$66$ cubic centimetres of silver is drawn into a wire $1$ mm in diameter. The length of the wire in metres will be

• A. $84m$
• B. $90m$
• C. $168m$
• D. $136m$

Answer 1

Answer: (A)

$84m$

Given volume of the wire $=66cubiccm$

Diameter $=1mm$

So, radius $=\frac{1}{2}\times {10}^{-1}cm$

Vol.of wire $=\pi r^{2}l$

$\Rightarrow 66=\frac{22}{7}\times \frac{1}{2^2}\times {10}^{-2}\times l$

$\Rightarrow l=\frac{66\times 7\times 2^2}{22\times {10}^{-2}}=8400$

Thus, the length of the wire $=8400cm=84m$