$1.$ A cylindrical workpiece is forged in a cold state. The initial height is $60$ mm and the diameter is $58$ mm$.$ In the operation the height is reduced to $20$ mm$.$ The work material has a flow curve with K $=350$ MPa and n $=0\mathrm{.}17.$ If the friction coefficient is $0\mathrm{.}15,$ determine the force:a$)$ when the process starts $($assume a very small strain value of $0\mathrm{.}002)$b$)$ at a height of $40$ mm and $30$ mm$,$ andc$)$ at a final height of $20$ mm$.$