A crane has a loading hook that is hanging in a steel wire. The allowable normal tensile stress in the wire gives an allowable force of 100,000 N. Estimate the safety factor that should be used.
a- The wire material is not controlled, the load can cause impact, and fastening the hook to the wire causes stress concentrations.
b- The wire material is extremely well controlled, no impact loads are applied and the hook is fastened in the wire without stress concentrations.