In the design of shafts made of ductile materials subjected to twisting moment and bending moment, the recommended theory of failure is

In an engineering drawing one finds the designation of $$20G7F8.$$ The position of tolerance of the hole is indicated by

Cutting speed in grinding is set to a high value to

The standard specification of a grinding wheel is $$A-46-M-6-V-21.$$ It means a wheel of