The box leaves position x=0 with speed v0. the box is slowed by a constant frictional force until it comes to rest at position x=x1. find ff, the magnitude of the average frictional force that acts on the box. (since you don't know the coefficient of friction, don't include it in your answer.) express the frictional force in terms of m, v0, and x1.

the electric field is a “force field” around a charged object that illustrates the direction the electric force would push an imaginary 

pretty sure it's false

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.

electric field is a function of 1/r^2

yes, the force per unit charge for a point charge is inverse square law.