This problem is the combination of two shape that is sphere and cylinder. To find answer of this question we need to use volume of sphere and volume of cylinder formulas. Problem number 17 from RS Aggarwal book exercise 17B, page number 810, chapter volume and surface area of solid.

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# 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 the wire

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Given data,

Diameter of sphere = 42 cm

Radius of sphere = 21 cm

Volume of sphere = [4/3] Ï€rÂ³

= [4/3] Ï€ Ã— 21Â³

Diameter of wire = 2.8 cm

Radius of wire = 1.4 cm

length of the wire = l cm

Volume of the wire = Ï€rÂ²l

= Ï€ Ã—1. 4 Ã—1. 4 Ã—l

Now,

Volume of the sphere =Â volume of the wire.

âˆ´ [4/3] Ï€ Ã— 21Â³ = Ï€ Ã—1. 4 Ã—1. 4 Ã—l

[4/3]Â Ã— 21Â³ = 1. 4 Ã—1. 4 Ã—l

l = ( [4/3]Â Ã— 21Â³) / 1.4 Ã— 1. 4

l = 6300 cm

l = 63 m

âˆ´ Length of the wire is 63m