Question

the force between two charge spheres -q and 3q are separated at a distance is f. if they are kept in contact and then separated to some distance. find the magnitude and nature of the force between them

Answer 1

Is this a trick question where Coulomb's Law does not apply?

Answer 2

Before contact
F = k q1 q2/d^2 = - 3 k q^2 /d^2 attracting each other
after contact each has charge 1 q
F = k q^2 /d^2 flying apart