Question

An iron rod of diameter 1cm and length 8cm is drawn into a wire of length 18m of uniform thickness. Find the thickness of the wire?

• A. 0.05 cm
• B. 0.06 cm
• C. 0.08 cm
• D. 0.09 cm

Answer 1

The correct option is B

0.06 cm

Volume of the rod = $\pi r^{2}h=\left(\pi \right)\times (\frac{1}{2}{)}^2\times 8=2\pi c{m}^3$

Volume of the wire = $\pi r^{2}h=\left(\pi \right)\times (r{)}^2\times 1800=1800\pi r^{2}c{m}^3$

Volume of the rod (old solid shape) = Volume of the wire (New solid shape)

2 $\pi =1800\pi r^2$

$r^2=\frac{1}{900}$

r = $\frac{1}{30}$

Diameter = $\frac{1}{15}=0.06cm$