Question

A steel wire of length 4.7 m and cross-sectional area 3.0 x 10-5 m2 stretches by the same amount as a copper wire of length 3.5 m and cross-sectional area of 4.0 x 10-5 m2 under a given load. What is the ratio of the Young'* modulus of steel to that of copper?

Answer 1

For steel, length of wire,

Ls = 4.7 m

Area of cross-section,

as = 3 x 10-5 m2

For copper length of wire Lc = 3.5 m

Area of cross-section, ac = 4.0 x 10-5 m2

If F be the stretching force, l be the increase in length in each case and Ys and Yc be the Young'* modulii of steel and copper respectively, then