Problem $2(6$ points$)$

$2\mathrm{.}1$ How does the stress$-$strain curve of steel help in understanding its behavior under tensile loads? Draw and explain the key regions of the stress$-$strain curve. Provide the formula to find Young's modulus of steel.

$2\mathrm{.}2$ A steel specimen with a gauge length of $50$ mm and diameter of $10$ mm is subjected to a tensile load. The elongation measured at the point of fracture is $2\mathrm{.}5$ mm $,$ and the maximum tensile load applied is $6000$ kg $.$ Calculate the ultimate tensile strength of the specimen.