a solid copper sphere of radius 3cm is melted and electric wire of diameter 0.4cm is made out of the copper obtained. find the length of wire?
The sphere and the wire will have the same volume.
volume of sphere = 4/3 * pi * 33 = 4/3 * pi * 27 = 36pi
volume of wire = area of cross section * length = pi * (0.4/2)2 * length = 0.04pi * length
volume of sphere = volume of wire
36pi = 0.04pi * length Divide both sides of this equation by 0.04pi .
900 = length
So the wire's length is 900 cm .