In this question we have to find the thickness of the wire given that a copper rod of diameter 1 cm and length 8 cm is drawn into a wire of length 18 m of uniform thickness.

If you open math book you will find a lot of mathematical questions but you should have solve this question.

It is from class 10 rd sharma chapter 16 mensuration .

Given,

Diameter of the copper wire = 1 cm

So, radius of the copper wire = 1/2 cm = 0.5 cm

Length of the copper rod = 8 cm

We know that,

Volume of the cylinder = π r2h

= π × 0.52 × 8 ……. (i)

Length of the wire = 18 m = 1800 cm

Volume of the wire = π r2h

= π r2 × 1800 ….. (ii)

On equating both the equations, we have

π × 0.52 × 8 = π r2 × 1800

r2 = 2 /1800 = 1/900

r = 1/30 cm

Therefore, the diameter of the wire is 1/15 cm i.e. 0.67 mm which is the thickness of the wire.