Four electrons are located at the corners of a square 10.0 nm on a side, with an alpha particle at its midpoint. How much work is done by the Coulomb force when the alpha particle moves to the midpoint of one of the sides of the square?
Express your answer in joules.

Four electrons are placed at the corner of a square

So we will first find the electrostatic potential at the center of the square

So here it is given as

here

r = distance of corner of the square from it center

now the net potential is given as

now potential energy of alpha particle at this position

Now at the mid point of one of the side

Electrostatic potential is given as

here we know that

now potential is given as

now final potential energy is given as

Now work done in this process is given as

0.19 m/s and 0.45 m/s

double the distance = divide strength by 4