I have read about the electrostatic force so it is said that charges must be at rest, but in some exercises, the electrostatic force between the electron and the proton in an atom is calculated. These exercises themselves say that the electron has a speed $v$ around the proton.
According to this situation, I would expect that the Coulomb's law must not be applied here because the electron is moving around the proton but the exercise uses the Coulomb's law to calculate the force acting on the electron.
I have read that the electrostatic force can be also applied to the interaction among atoms in molecules and among atoms and molecules. In this last cases shall we assume the relative speed of each atom relative to another is zero? I say this because the molecules could move.