Question $1(2$ points$)$

Stress$-$strain behaviour of ceramics is usually determined through a three$-$point bending test due to their brittle behaviour. Such a test is performed on a spinel specimen of MgO having a rectangular cross section of height $d=3\mathrm{.}8mm(0\mathrm{.}15$ in $.)$ and width $b=9mm(0\mathrm{.}35$ in $.)$; the distance between the support points is $25$ mm $(1\mathrm{.}0$ in $.).$ Compute the flexural strength of the specimen if the load at fracture is $350N(80lbf).$