A2.0 g metal cube and a 4.0 g metal cube are 6.0 cm apart, measured between their centers, on a horizontal surface. for both, the coefficient of static friction is 0.65. both cubes, initially neutral, are charged at a rate of 7.0 nc/s .

(a) which cube moves first?

(b) how long after charging begins does one cube begin to slide away?

(a).  The 2.0 g metal cube move fast than the 4 g metal cube.

(b). The time taken is 10.19 sec.

Explanation:

Given that,

Mass of metal cube = 2.0 g

Mass of second metal cube = 4.0 g

Coefficient of static friction = 0.65

Charging rate = 7.0 nC/s

Distance = 6.0 cm

(a). We need to calculate the frictional force for 2.0 g metal cube

Using formula of frictional force

Put the value into the formula

The frictional force for 4.0 g metal cube

The motion of the cube is less when the friction is more.

The 2.0 g metal cube is having less frictional force.

Therefore, the 2.0 g metal cube move fast than the 4 g metal cube.

(b). We need to calculate the time

Firstly we need to calculate the charge

Using electrostatic force and frictional force

Put the value into the formula

The time taken after charging beings is

Put the value into the formula

Hence, (a).  The 2.0 g metal cube move fast than the 4 g metal cube.

(b). The time taken is 10.19 sec.

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.