Answer:

Step-by-step explanation:
mass of each ball, m = 1 kg
Let the charge on each ball is q.
If the balls remains fix then the gravitational force is balanced by the electrostatic force between them and as the gravitational force is attractive in nature then the electrostatic force should be repulsive in nature.
The charges should be of same sign to get the electrostatic force is repulsive in nature.
Let the distance between the two balls is d.
The electrostatic force between them is given by
... (1)
The gravitational force between the two balls is given by
... (2)
according to the question, gravitational force is equal to the electrostatic force, so by equation (1) and (2) ,we get





Thus, the charge on each ball is
