42. A thin silk thread withstands the maximum tension force T = 10 mN. A ball of mass m = 0.6 g, having a positive charge q1 = 11 nC, is suspended on this thread. From below, in the direction of the suspension line, a ball with a negative charge q2 = −13 nC is brought to it. At what distance r between the balls does the thread break?

Detailed solution. Decorated in Microsoft Word 2003. (Target decided to use formula editor)