Two identical charged spheres suspended from a
common point by two massless strings of lengths
l, are initially at a distance d (d << l ) apart because
of their mutual repulsion. The charges begin to leak
from both the spheres at a constant rate. As a result,
the spheres approach each other with a
velocity v. Then v varies as a function of the
distance x between the spheres, as :
(1)V ``\propto `` ``X^{\frac 12}``
(2)V ``\propto `` X
(3)V ``\propto `` ``X^{-\frac 12}``
(4) V ``\propto `` ``X^{-1}``