The correct answer is 0,1. Key Points Formula for speed after impact va =/(ma + mb) {1} vb =/(ma + mb) {2} Where, va = Velocity of a after impact vb = Velocity of b after impact ua = Velocity of a before impact ub = Velocity of b before impact CR = Coefficient of restitution Ma = mass of object a Mb = Mass of object b Let us consider, Object a = ball and object b = gate Now given in question: ua = 2m/s ub = 0 m/s Let, Mb = x the mb = 2x CR = 0.5 Now putting the values in equation {1} va = / x + 2x = /3x = /3x = 0/3x m/s = 0 m/s vb = / (x + 2x) = /3x = 3x/3x = 1 m/s So, after impact speed of Ball = va = 0 m/s Gate = vb = 1 m/s Thus the answer is 0, 1.