A steel wire and a copper wire of equal length and equal cross-sectional area are joined end to end and the combination is subjected to a tension. Find the ratio of (a) the stresses developed in the two wires and (b) the strains developed. Y of steel = 2×1011Nm−2. Y of copper = 1.3×1011Nm−2.
Given that, Lsteel=LCu
and Asteel=ACu
(a)stress of CuStress of Steel=FCu ASteelACuFSteel
=FCuFSteel=1 [because FCu=FPSteel]
(b) Strain=Δ LSteelΔL Cu
=FSteelLSteel AcuYcuASteelYSteelFcuIcu
[Lcu=LSteel:Acu=ASteel]
⇒YcuYSteel=1.3×10112×1011
⇒ΔLSteelΔIcu=1320
⇒ΔLcuΔLSteel=2013