A spring is connected to an elastic bar as shown in the figure. The spring has a stiffness constant of $10^{7} \mathrm{~N} / \mathrm{m}$. The bar is 70 mm long, and has an area of crosssection $10 \mathrm{~mm}^{2}$. The Young's modulus of the bar material is $70,000 \mathrm{MPa}$. A force $F=5000 \mathrm{~N}$ is applied at point $O$ along the axis of the bar and the spring. The resulting deflection of Point $O$ in mm $\text{(rounded to one decimal place)}$ is ___________.
