Q36 of 107 Page 16

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

Diameter of copper wire =1 cm


Radius cm


Height of copper rod =Length of copper rod =8 cm


Volume of rod



Let the radius of wire be ‘r’ cm


Height of the wire =18 m =0.18 cm


Volume of cylinder wire = Volume of cylindrical rod




⇒ r2


⇒ r cm


⇒ r = 1/3 mm


∴ Diameter of cross section = (1/3) × 2 mm


= 0.67 mm


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