The athlete ran several full laps along the stadium track. Is the trajectory of its movement closed:
a) relative to the Earth;
b) relative to the Sun?
the trajectory is closed relative to the earth, but not closed relative to the sun, since until he made a circle the earth managed to shift relative to the sun and he cannot return to the same point.
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.