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

For a two dimensional state-of-stress defined as $${\sigma _{xx}} = {\sigma _{yy}} = {\tau _{xy}} = S,$$ the Mohr's circle of stress has

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