Plot on log$-$log coordinates estimated $S-N$ curves for

$($a$)$ bending, $($b$)$ axial, and

$($c$)$ torsional loading of a $3\mathrm{.}5-$in$.-$diameter steel bar having $S_u=97$ksi and $S_y=68$ksi and

machined surfaces. For each of the three types of loading, what is the fatigue strength corresponding to $(1){10}^6$ or more cycles and $(2)5*{10}^4$ cycles