Q$1.[14$ points$]$ A bar having a length of $180$ mm and cross$-$sectional area of $300m{m}^2$ is subjected to

an axial force of P $.$ If the bar stretches $0\mathrm{.}04$ mm $,$ and the modulus of elasticity of the material is $12$ GPa $,$

then determine the value of applied force, P$.$ Assume that the material behavior is linear$-$elastic.