Suppose a solid disk of positive charge with radius R and a uniform surface charge density σ is located in the xy-plane, centered on the z-axis. Very far above the disk there is an electric dipole oriented in the vertical direction with dipole moment p and total mass 2m, initially at rest.

Over time the dipole slowly begins to accelerate towards the center of the disk, which has a small hole in the middle through which the dipole can pass. What is the maximum speed that is achieved by the dipole?

Enter your answer in terms of R, σ, p, m, and ϵ ₀ .