How do the phases of the driving force and the force of viscous friction relate when the cyclic frequency of the driving force is √k / m?

In this case, the phases of the driving force and the force of viscous friction are opposite.

Remember: The process of learning a person lasts a lifetime. The value of the same knowledge for different people may be different, it is determined by their individual characteristics and needs. Therefore, knowledge is always needed at any age and position.