Two small charged balls have a repulsive force of 0.12 N when they are separated by a distance of 0.85 m. The balls are moved closer together, until the repulsive force is 0.60 N. How far apart are they now?

Answer 1

For the repulsive force to increase by a factor of 5, the distance must decrease by a factor of sqrt5 = 2.236

That would make the new distance 0.380 m