A 200. kg box is pulled at constant speed by the little engine pictured below.  The box moves a distance of 2.5 m across a horizontal surface.          

a)    Draw a force diagram of all relevant forces acting on the box.   
   
b)    Construct a qualitative energy bar graph/flow diagram for this situation.  Be sure to specify your system.

c)    How much energy is transferred by the engine?

d)    What type of motion would occur if the engine pulled with a force of 500 N?
    Modify your force diagram and apply Newton's 2nd Law.

reserve is the answer

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.