The femur is a bone in the leg whose minimum cross$-$sectional area is about $4\mathrm{.}4$ x $10-4$ m$^2.$ A compressional force in excess of $7\mathrm{.}0$ x $104$ N will fracture this bone. Bone has a compressional Young's modulus of $9\mathrm{.}4$ x $109$ N$/$m$^2.($a$)$ Find the maximum stress that this bone can withstand. $($b$)$ What is the strain that exists under a maximum$-$stress condition?