In their first experiment with the apparatus, the students use the double incline to measure the unknown mass of block b. they do this by fixing the value of the right incline at θ=20.0° and then adjusting the value of ϕ for the left incline such that both blocks remain at rest. they find the left incline must be tilted such that ϕ=43.0° . (you can do this experiment for yourself with the simulation! ) what is the mass of block b, mb ?

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.