Find the moment of inertia (a) of a thin uniform rod relative to the axis which is perpendicular to the rod and passes through its end, if the mass of the rod is \(m\) and its length \(l\) (b) of a thin uniform rectangular plate relative to the axis passing perpendicular to the plane of the plate through one of its vertices, if the sides of the plate are equal to \(a\) and \(b,\) and its mass is \(m\)