Given: A copper rod of diameter 1 cm and length 8 cm is drawn into a wire of length 18 m of uniform thickness.
To find: the thickness of the wire.
Diameter of copper wire =1 cm
Height of copper rod =Length of copper rod =8 cm
Volume of rod
Let the radius of wire be ‘r’ cmAs 1 m = 100 cm
length of the wire=Height of the wire =18 m =1800 cm
As rod is converted into wire,
Volume of cylinder wire = Volume of cylindrical rod
As radius cannot be negative,
⇒ r = 0.033 cm
Hence thickness of the wire is 0.033 cm.
⇒ r cm
⇒ r = 1/3 mm
∴ Diameter of cross section = (1/3) × 2 mm
= 0.67 mmNOTE: When one figure is converted into another figure,
the volume of two figures remain same.
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