a) F = \(F_{13}+F_{23}=\frac{k\cdot8\cdot10^{-8}\cdot8\cdot10^{-8}}{0,03^2}+\frac{k\cdot8\cdot10^{-8}\cdot8\cdot10^{-58}}{0.03^2}=0.128\left(N\right)\)
b) F = \(F_{13}+F_{23}=\frac{k\cdot8\cdot10^{-8}\cdot8\cdot10^{-8}}{0,04^2}+\frac{k\cdot8\cdot10^{-8}\cdot8\cdot10^{-8}}{0,02^2}=0,18\left(N\right)\)
c) F = \(\left|F_{13}-F_{23}\right|=\left|\frac{k\cdot8\cdot10^{-8}\cdot8\cdot10^{-8}}{0,04^2}-\frac{k\cdot8\cdot10^{-8}\cdot8\cdot10^{-8}}{0,1^2}\right|=0,03024\left(N\right)\)
d) F = \(\sqrt{F_{13}^2+F^2_{23}+2\cdot F_{13}\cdot F_{23}\cdot\cos60}=0,0277\left(N\right)\)