To find the radius formed by melting the wire, you must start with this equation:
volume of wire = volume of sphere (since it is simply melted into a different shape, the volume would remain the same, equal)
πr²l = 4/3πr³
cancel π:
r²l = 4/3r³
3r²l = 4r³
r³ = (3r²l)/4
r³ = (3 × 3² × 200)/4
r³ = 1350
r = (cube root) of 1350
r = 11.052094....
r = 11.05 mm
divide by 1000 to get the answer in the unit meters:
r = 0.01105m
