An electric dipole consists of two point charges $(\pm q),$ each of mass $m,$ fixed to the ends of a (mass less) rod of length $d .$ (Do not assume $d$ is small.)
(a) Find the net self-force on the dipole when it undergoes hyperbolic motion (Eq. 12.62 ) along a line perpendicular to its axis. [Hint: Start by appropriately modifying Eq. $11.90 .$
(b) Notice that this self-force is constant ( $t$ drops out), and points in the direction of motion $-$ just right to produce hyperbolic motion. Thus it is possible for the dipole to undergo self sustaining accelerated motion with no external force at all! $1^{18}$ [Where do you suppose the
energy comes from?] Determine the self-sustaining force, $F$, in terms of $m, q,$ and $d$.