A cylindrical copper rod of diameter 1 cm and length 8 cm is drawn into a cylindrical wire of length 18 m and of unifiorm thickness. Find the thickness of the wire.

**Cylindrical rod:**

Diameter (*D*) = 1 cm

⇒ Radius (*R*) =

Height of rod (*H*) = length of rod = 8 cm

∴ Volume of rod = π*R*^{2}*H*

Cylindrical rod is drawn into a cylindrical wire of length (*h*) 18 m (= 1800 cm)

∴ Volume of cylindrical rod = volume of cylindrical wire

Let *r* be the radius of cross-section of the wire.

So, the diameter of the cross-section (approx)

Hence, thickness of the wire = 0.67 mm (approx)

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