An arrangement of two particles each having charge Q= -6.8 nC and each separated by 5.0 mm from a proton. If the two particles are held fixed at their locations and the proton is set into motion from the middle point. What is the minimum speed the proton needs to totally escape from these particles? (m proton= 1.67 x 10^-27 kg, e= 1.60 x 10^-19, k= 9.0 x 10^9).