Answer: find the attached files for the answer
Explanation:
The reflected ray appears to have originated from the focal point. We should actually draw a vector from the focal point through the point where the incident ray hits the mirror but we shorten the vector so that its starting point is on the mirror, without changing its angle.
Please find the attached files for the solution
1) In the reference frame of one electron: 0.38c
To find the relative velocity of one electron with respect to the other, we must use the following formula:

where
u is the velocity of one electron
v is the velocity of the second electron
c is the speed of light
In this problem:
u = 0.2c
v = -0.2c (since the second electron is moving towards the first one, so in the opposite direction)
Substituting, we find:

2) In the reference frame of the laboratory: -0.2c and +0.2c
In this case, there is no calculation to be done. In fact, we are already given the speed of the two electrons; we are also told that they travel in opposite direction, so their velocities are
+0.2c
-0.2c
Explanation:
it is given that, the linear charge density of a charge, 
Firstly, we can define the electric field for a small element and then integrate for the whole. The very small electric field is given by :
..........(1)
The linear charge density is given by :


Integrating equation (1) from x = x₀ to x = infinity



Hence, this is the required solution.
The diagram shows components that have been added together to form Rx and Ry. Rx and Ry are the components of the resultant vector.
Which formula can be used to find the angle of the resultant vector?
the answer is C
C. tan0= Ry/Rx