The equations for calculating both the electric force and the gravitational force are above. Their equations are very similar. What is an important difference between these two forces? A The electrical force is measured in coulombs; the gravitational force is measured in newtons.

B The electrical force between two charged objects will always be weaker than the gravitational force between them.

C The gravitational force decreases with the square of the distance between the objects; the electrical force increases with the square of the distance between the objects.

D Electrical forces can be attractions or repulsions; gravitational forces can only be attractions.

A, B, and C are hilarious. D is correct.

Charges can be positive or negative, so a pair of charges can be alike or opposite. But so far, we've never seen a negative mass.

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.