Internal loading

$($a$)$ List the steps for calculating internal loading at point $D$ in ule beam above. $(8)$

$($b$)$ What is the sign of the normal force at point $B?(5)$

$($c$)$ Describe the sign conventions for internal loading: what condition corresponds to

positive or negative values of $N,V$ and $M?(6)$

$($d$)$ Are the values of normal and shear forces, and moment, different if you calculate

the loading from the left part or right part of the beam? Briefly explain. $(8)$