A person pushes two boxes with a horizontal 100 N force on a frictionless floor, as shown in the figure. Box A is heavier than box B. Which statement about these boxes is correct? The boxes move with constant velocity. A. Box A pushes on box B harder than box B pushes on box A.
B. Box A pushes on box B with a force of 100 N, and box B pushes on box A with a force of 100 N.
C. Boxes A and B push on each other with equal forces of less than 100 N.
D. The boxes will not begin to move unless the total weight of the two boxes is less than 100 N.

it was given as a lesson and guide for prayer.

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.