8.1 A steel wire of length 4.7 m and cross-sectional area
3.0\times 10^(-5)m^(2)
stretches by the same amount as a copper wire of length 3.5 m and cross-sectional area of
4.0\times 10^(-5)m^(2)
under a given load. What is the ratio of the Young's modulus of steel to that of copper?