Question

Two charged Ping-Pong balls separated by a distance of 1.20 m exert an electric force of 0.0300 N on each other. What will be the force if the objects are brought closer, to a separation of only 30.0 cm?

_____N

Answer 1

Ever heard of the inverse square law?
Coulomb's law in one of them.

According to that law, 1/4 the distance results in 16 times the force.