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