A machined surface with standard symbols indicating the surface texture is shown in the Figure. (ALL dimensions in the Figure are in micrometer).

The waviness height (in micrometer) of the surface is

Accuracy of a measuring instrument is expressed as

If $$E$$ is the modulus of elasticity in $$GPa$$, $$G$$ is the shear modulus in $$GPa$$ and $$v$$ is the Poisson's ratio of a linear elastic and isotropic material, the three terms are related as

The inside and outside radii of a thick- walled cylindrical pressure vessel are denoted by $$a$$ and $$b,$$ respectively. If the vessel is subjected to an internal pressure $$P,$$ then the magnitude of the radial stress $${\sigma _{rr}}$$ is