# Uniform distribution of charge on a plane and on a bar: conditions to

On the plane z=0 there is a superficial charge distribution such that $\sigma$ is constant.

Near to the plane, there is a bar, charged uniform with total charge q. At the extremities the bar has two constraints, so it can't turn.

If I want to find the constraints force and the force momentum needed to block the bar, can I consider the charge q as puntiform and put it in the midpoint of the bar?