The diameter of a sphere is 42 cm. It is melted and drawn into a cylindrical wire of diameter 2.8 cm. Find the length of wire.
Given,
Diameter of sphere = 42 cm
Radius of sphere = 21 cm
Volume of sphere = 
πr3 = 
× π × 21 × 21 × 21 cm3
Diameter of cylindrical wire = 2.8 cm
Radius of cylindrical wire = 1.4 cm
Volume of cylindrical wire = πr2h = π × 1.4 × 1.4 × h cm3 = 1.96πh cm3
Volume of cylindrical wire = volume of sphere
1.96πh = 
× π × 21 × 21 × 21
h = 
cm
h = 6300
h 
m = 63 m
Hence, length of the wire = 63 m
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