$($d$)$ Use classical equations to calculate the bending stress at the top and bottom of the member.

AB at section Z$-$Z$.[10$ points$]"$L$"-$shaped cantilever beam, shown in Figure $4,$ is rigidly supported at its left end,

point $A,$ and subject to a downward force of $1500$ N applied to the vertical face at endpoint $C.$

Cylindrical rod $AB$ is made of Alloy Steel. At the same time, the material of rectangular member

$BC$ is $2014-$T$6$ Aluminum. Materials for these two components are given as follows:

Cylindrical member, AB: Alloy Steel $($Use SI units$)$

Rectangular member, BC: $2014-$T$6$ Aluminum $($Use SI units$)$