If the Poisson's ratio of an elastic material is $$0.4$$, the ratio of modulus of rigidity to Young's modulus is _____ .

A steel cube, with all faces free to deform, has Young’s modulus, $$E,$$ Poisson’s ratio, $$ν,$$ and coefficient of thermal expansion, $$\alpha .$$ The pressure (hydrostatic stress) developed within the cube, when it is subjected to a uniform increase in temperature, $$\Delta T,$$ is given by

The stress-strain curve for mild steel is shown in the figure given below. Choose the correct option referring to both figure and table

A rod of length $$L$$ having uniform cross-sectional area $$A$$ is subjected to a tensile force $$P$$ as shown in the figure below. If the Young’s modulus of the material varies linearly from $${E_1}$$ to $${E_2}$$ along the length of the rod, the normal stress developed at the section $$-$$ $$SS$$ is