Quandaries and Queries


The radius of a copper sphere is 3cm. If  a wire of  0.4 diameter is drawn by melting it,what is the length of this wire?



When you change the shape of the copper from a sphere to a long cylindrical wire, the amount of copper doesn't change. By the amount I mean the volume so the volume of the copper sphere and the volume of the cylinder are the same.

The volume of the sphere is

 4/3 r3 =  4/3 33 = 36

The volume of the cylinder is

r2 h = 0.042 L

Since the volume is unchanged

36 = 0.042 L

Solve for L.



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