Problem 2

 When two electric charges occupy the positions shown in Figures 1 and 2, the values of the Coulomb force between the charges are known, respectively F₁ and F₂.

Find the force of the Coulomb interaction of charges when they occupy the position shown in Figure 3.

Problem 1

Two point-objects carrying the same electric charge are keeping at some distance from each other by a string, which exerts on objects only its known tension force T₁ and does not participate in electrostatic interaction.
If four such point-objects with the same as previous charges are attached to a string at the same distance from each other as before, what will be the tension T₂ in the middle of the string?