Question

A copper rod of radius 1 cm and length 10 cm is drawn into a wire of length 40 m of uniform thickness. Find the diameter of the wire.

Answer 1

... 8 cm is drawn into a wire of length 18 m of uniform thickness. Find the thickness of the wire. ... is in form of cylinder with Diameter of rod = 1 cm So, radius ...

Answer 2

Copper rod
r1 = 1 cm
h1 = 10 cm

Wire
r2 =?
h2 = 40 m
40 metres is equal to 4000 cm
Volume of rod = volume of wire

$\pi ({r1})^{2} h1 = \pi ({r2})^{2} h2$
${1}^{2} \times 10 \: = ({r2})^{2} \times 4000$
$10 \div 4000 = ({r2})^{2}$
$( {r2})^{2} = 1 \div 400$
$r2 = \sqrt{1 \div 400}$
$r2 = 1 \div 20$
$r2 \: = 0.05 \: cm$

$so \: diameter \: is \: 0.10 \: cm$