A $20-$mm$-$diameter steel $)=200$GPa,$v=(0\mathrm{.}28$ tension rod is $2$ meter long and carries a load of $4500N.$

a$.$ Calculate tensile stress $($ MPa $)$

b$.$ Calculate tensile strain

c$.$ Change in length of the rod $($mm$)$

d$.$ Decrease in diameter of the rod $(mm)($positive number$)$