You can do this all in one Step
Formula
F2/F1 = 8.5/(25r^2) // 1 / r^2
Solution
[tex]\dfrac{F2}{F1} = \dfrac{\dfrac{k8.5*q1*q2}{(5r)^2}}{\dfrac{k*q1*q2}{r^2} }[/tex]
The "ks, r^2 and q1 q2" all cancel out
You are left with 8.5/25 as the ratio
- F1 = 5.7 N
- F2 = 8.5 / 25 * F1
- F2 = 8.5 / 25 * 5.7
- F2 = 1.938
