The force between two objects, each of charge -Q is measured as +F when the objects are separated a distance 2d apart. If the charge on only one object is tripled, determine the new force between them:

Fnew = k (-3Q *(-Q)) / (2d)²

Fnew = k * 3Q² /4d²

Explanation:

This is Coulomb's law

F = k (q₁*q₂)/r²

F - electric force

k - Coulomb constant

q₁, q₂ - charges

r - distance of charges

Starting situation :   q₁ = -Q, q₂= -Q , r =2d

F = k (-Q*(-Q)) / (2d)²

F = k *Q² /4d²

NEW FORCE :  q₁ = -3Q, q₂= -Q, r =2d

Fnew = k (-3Q *(-Q)) / (2d)²

Fnew = k * 3Q² /4d²

dynamic equilibrium is the answer.