The text is following: Two balls are hanged on a stative from the same point with 5 cm threads. If they both had the same charge they would be 6 cm away from each other. Both balls weigh 10 mg. Find the charges. I think the first step is to find the amount of force needed, but I don´t know how. Then I should be able to find the charges from F=k*q1*q2/r*r. I know it´s easy but could please someone tell me what force I should calculate?