Answer:
Step-by-step explanation:
Kinetic energy of ball in motion = 1/2 m v² . Potential energy = 0
Let the minimum distance between the balls be d on collision.
Electric potential energy at that time= k Q²/d , Here kinetic energy is converted into potential energy . So
1/2 m v² = kQ²/d
d =2 k Q² / mv²,= 18 x 10⁹ x Q²/ m v².