The electric force between two objects with charge q1 and q2 is given by
[tex]F=k_e \frac{q_1 q_2}{d^2} [/tex]
where ke is the Coulomb's constant while d is the distance between the two charges.
We can see that the force F scales as the inverse of the square of the distance: [tex] \frac{1}{d^2} [/tex]. Therefore, when the two objects move apart from each other, the distance increases and therefore the force between them decreases.
