For the $30$ m long beam shown below, first calculate the reaction forces. Then:

a$)$ Draw a partial FBD of the beam from $x=3m$ to the right end of the beam $($shown below$).$

At the cut surface at $x=3m,$ three unknown internal forces are exposed:

Axial Force N $($perpendicular to the cut surface, this is the same as tension$/$compression forces$)$

Shear Force V $($parallel to the cut surface$)$

Bending Moment M

Use equations of equilibrium to solve for these unknown internal forces, $N,V,M,$ at $x=3m.$ Plot the value V $($at x $=3m)$ on the shear force diagram $($SFD$)$ at $x=3m$ and