A force F is applied along a rod of transverse section area A the normal stress to a section PQ inclined theta to a transverse section is

​Q10. A force F is applied along a rod of transverse section area A. The normal stress to a section PQ inclined $\mathrm{\theta }$ to transverse section is
           

        ​(1) $\frac{\mathrm{F} \sin \mathrm{\theta }}{\mathrm{A}}$                                              (2) $\frac{\mathrm{F} }{\mathrm{A}} \mathrm{cos\theta }$

        ​(3) $\frac{\mathrm{F} }{2\mathrm{A}}\sin 2\mathrm{\theta }$                                          (4) $\frac{\mathrm{F} }{\mathrm{A}}{\cos }^2\mathrm{\theta }$