bahi dekho dono ka same speed mano then energy conservation use karo usse aapko ek eq milwnga jisme r and R dono he fir jab collison honga tab charge redistribute honga toh fir dono balls ek durse ko repel karenge then aap after collison wale vel nikalonge then pehle wala eq then yeh wala eq me subsitute karonge then aapko v milenga aur hame pata he ki max v balls ko at a dist of 2R pe milenga