Question

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

Answer 1

Diameter (D) = 1 cm
⇒ Radius (R) =
Height of rod (H) = length of rod = 8 cm
∴ Volume of rod = $\pi R^{2}H$
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)