Q:6DTQ Two particles of mass m and 2m carry a charge q each.Initially the heavier particle is at rest on a smooth horizontal plane and the other is projected along the plane directly towards the first from a distance d with speed u.If the closest distance of approach is `(3q^(2)d)/(nq^(2)+4 pi varepsilon_(0)u^(2)d)` then find the value of n .