A steel wire and a brass wire are joined end to end and are hung vertically with the steel wire attached to a point on the ceiling. The steel wire is twice as long as the brass wire and has half the diameter. A large mass is hung from the end of the brass wire so that both wires are stretched elastically. The Young modulus for steel is 
and for brass is 
. What is the ratio of the extension of the steel to the extension of the brass?
2
4
8
16
