Question

the radius of a metallic sphere is 9 cm. It was melted to make a wire of diameter
4 mm. Find the length of the wire.
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Answer 1

Good Morning!

Here, Surface area of sphere = surface of cylindrical wire.

Surface area of sphere = 4πr²

And

Surface area of cylindrical wire = 2πRh

Where h is height of wire And R is radius of wire. Here D = 4mm = 4 × 10-1cm

D = 2/5cm R = 1/5cm

4πr² = 2πRh

4π ( 9 )² = 2π ( 1/5 )² h

162 = 4h/25

h = 4050

So, Height of cylindrical wire is 4050cm