Answer:
a.
experiences the greatest net force and
experiences the smallest net force
b. Ratio of the greatest to the smallest net force= 9
Explanation:
<u>Electrostatic Forces
</u>
Two point-charges q1 and q2, separated a distance d, exert on each other an electrostatic force of magnitude

If the charges have the same sign, they repel each other, for different signed charges, they attract. That gives us the direction of each force in the space.
Let's assume all the charges of the problem have a magnitude q, and between two consecutive charges, the distance is d. The proposed layout is shown it the image.
a.
The net force on qA is the sum of those exerted by qB, qC, and qD. But note qB and qC repel qA and qD attracts it, so the total force on qA is

Computing the individual forces we have



The total force on qA is:



Charge qA repels qB to the right, qC repels qB to the left, and qD attracts qB to the right, thus




Charges qA and qb repel qC to the right, and qD attracts qC to the right, thus




Charge qA and qB attract qD to the left, and qC atracts qD to the left, thus




Comparing the relative values of all the forces

This means that qc experiences the greatest net force and qB experiences the smallest net force
b.
The ratio of the greatest to the smallest forces is
