The maximum diameter of the hole that can be punched from a plate of maximum shear stress 1/4^{th} of its maximum crushing stress of punch, is equal to (where t = Thickness of the plate)

Two closely coiled helical springs 'A' and 'B' are equal in all respects but the number of turns of spring 'A' is half that of spring 'B' The ratio of deflections in spring 'A' to spring 'B' is

A thin cylindrical shell of diameter (d) and thickness (t) is subjected to an internal pressure (p). The ratio of longitudinal strain to volumetric strain is