A rectangular workpiece has the following initial dimensions: L$0=100$ mm$,$ h$0=30$ mm and width w$0=20$ mm $($see Fig. $2).$ The material has a yield strength Y$0$ of $90$ MPa, a strength coefficient K of $202$ MPa, and a strain hardening exponent n of $0\mathrm{.}13.$ It is to be reduced in height by $20\%($forged in plane strain$).$ Let the coefficient of friction between the workpiece and die be $0\mathrm{.}2($dry friction$).(1)$ Calculate the force $[$kN$]$ required to initiate yielding of the workpiece. $(2)$ Calculate the force $[$kN$]$ required for a $20\%$ reduction in height