98. A ball of mass m = 2.0 g, having a charge q1 = 20 nC, is suspended in air on a thin non-conductive filament. From the bottom, at a distance of r = 50 mm vertically from it, the charge of the same name is strengthened q2 = 120 nC. The suspension point, charge and ball are on the same line. Determine the strength of the thread tension.

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