A solid copper sphere of surface area 1386 cm sq. is melted and drawn into a wire of uniform cross section . If the lenght of the wire is 31.5 m , find the diameter of wire !! 

Hi Afzal!
Here is the answer to your question.
 
Let r be the radius of the copper sphere.
Let R be the radius of the wire.
 
Length of the wire, H = 31.5 m
Given that surface area of the copper sphere is 1386 sq cm
 
∴ 4Πr2 = 1386 sq cm
 
 
The sphere is recasted to form the wire.
 
Thus, volume of the wire formed = Volume of the solid sphere

 
Thus, the diameter of the wire is 2 × 0.7 cm = 1.4c m
 
Hope! This will help you.
Cheers!

  • 10

Tip : Use the fact that a wire is in the form of a cylinder. The length of the wire means the height of the cylinder.

This kills the problem

  • -3
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