What happens to the length of the day due to refraction of light?

One of the consequences of this effect of refraction is that contrary to what most people think, the day and night is not exactly 12 hours long on the days of the Equinoxes. Because of refraction of sunlight, daytime is just slightly longer than night time on March Equinox and September Equinox. This effect also has an impact on the time that the Moon can be seen before Moonrise and after Moonset.

the displacement produced by the body.  

the amount of force subjected to the body.  

the angle between the direction of force and displacement

russian is not my first language, so i'm afraid i can't write out an answer in russian, but hopefully you can find a way to do so. here's my best translation of the problem: you're given a plot of a particle's position in one-dimensional space over time, and you're asked to find either the total distance traveled by the particle after 6 seconds had elapsed, or the total displacement of the particle after 6 seconds.

if you want the total distance traveled, you would first need to determine the particle's velocity as a function of time, then integrate that over the 6-second interval. we know the position function is quadratic with roots at 0 and 6, so we have

where is unknown. because the position is parabolic, there is symmetry about the midpoint at , and we know that

so that the position function is

which means the velocity is

then the total distance traveled is

so the total distance traveled is 20 m.

on the other hand, if you want to find displacement: the particle starts at and ends at , so its displacement is 0.