Two shells, suspended on silk threads, were pulled to each other and, after contact, hung vertically.

Two shells, suspended on silk threads, were pulled to each other and, after contact, hung vertically. Why are they attracted? Why did they stop interacting after contact? Two shells, suspended on silk threads, were pulled to each other and, after contact, pushed away from each other. Explain this phenomenon.

In the first case, before contact, the shells had equal charges, but different in sign. After contact, the excess electrons on the negatively charged sleeve passed to the sleeve that had a lack of electrons and completely neutralized the positive charge. The charge of both casings became zero, so they stopped interacting.
In the second case, the sleeves had charges of different sign and absolute value, which caused their attraction. On contact, part of the charges of one cartridge neutralized the charges of the other cartridge, and the excess charge was distributed to both cartridges. Having received the same charge, the sleeves began to repel.