Shouldn't the middle cross section area in part a$)$ be $($w x t$)-($D$2$ x t$)$ since there is a hole in the bar? Also shouldn't P for part $2$ be multiplied by $2,$ since there is a $0\mathrm{.}5$kN force on each side of the bar, as per the diagram. $($So P would be $1000$N$)$ Respective answers would be a$)57$ MPa and b$)4$MPa?