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

The number of independent elastic constants required to define the stress-strain relationship for an isotropic elastic solid 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

A metallic rod of $$500$$mm length and $$50$$mm diameter, when subjected to a tensile force of $$100$$kN at the ends, experiences an increase in its length by $$0.5$$mm and a reduction in its diameter by $$0.015$$mm. The Poisson's ratio of the rod material is _______ .