The steel bar shown has a $50 \mathrm{mm}$ by $10 \mathrm{mm}$ rectangular cross section. The allowable normal and shear stresses on inclined surface $\mathrm{a}-\mathrm{a}$ must be limited to $40 \mathrm{MPa}$ and $25 \mathrm{MPa}$, respectively. Determine the magnitude of the maximum axial force $\mathrm{P}$ that can be applied to the bar.