A uniformly charged disk is rotating around an axis that passes through the center of the disk and is perpendicular to the plane of the disk as shown in the figure. The angular speed of rotation is 3.9 rad/s. If the radius of the disk is 1.6 m and the electric charge density of the disk is 4 C/m², what is the dipole contribution to magnetic potential energy (in J) associated with the interaction between the disk and an external magnetic field with a magnitude of 0.4 T aligned parallel to the axis of rotation?