A charge −q₁ of mass m rests on the y axis at a distance b above the x axis. Two positive charges of magnitude q₂ are fixed on the x axis at x=−a and x=a respectively. If the −q₁ charge is given an initial velocity v₀ in the positive y direction, what is the minimum value of v₀ such that the charge escapes to a point infinitely far away from the two positive charges?