Answer:
1. Largest force: C; smallest force: B; 2. ratio = 9:1
Explanation:
The formula for the force exerted between two charges is

where K is the Coulomb constant.
q₁ and q₂ are also identical and constant, so Kq₁q₂ is also constant.
For simplicity, let's combine Kq₁q₂ into a single constant, k.
Then, we can write

1. Net force on each particle
Let's
- Call the distance between adjacent charges d.
- Remember that like charges repel and unlike charges attract.
Define forces exerted to the right as positive and those to the left as negative.
(a) Force on A

(b) Force on B

(C) Force on C

(d) Force on D

(e) Relative net forces
In comparing net forces, we are interested in their magnitude, not their direction (sign), so we use their absolute values.

2. Ratio of largest force to smallest

I would say that this is the first law of thermodynamics.
Answer:
Average speed = 1.2 m/s
Average velocity = 0.4 m/s
Explanation:
Average speed = total distance/total time
Average speed = (40 + 20)/(40 + 10)
Average speed = 60/50
Average speed = 1.2 m/s
Average velocity = displacement/time
Now, she ran 40 m south and ran 20 m back north which is in the direction of where she began the journey.
Thus;
Displacement = 40 - 20 = 20 m
Average velocity = 20/50 = 0.4 m/s