We can use Coulomb's law to solve the proble:
[tex]\begin{gathered} F_{31}=K\cdot\frac{q1\cdot q3}{r^2} \\ F_{31}=(8.988\times10^9)\cdot\frac{(2.6\times10^{-6})(1.3\times10^{-6})}{(0.2^2)} \\ F_{31}=0.759N \end{gathered}[/tex][tex]\begin{gathered} F_{21}=K\cdot\frac{q1\cdot q2}{r^2} \\ F_{21}=(8.988\times10^9)\cdot\frac{(2.6\times10^{-6})(3.75\times10^{-6})}{(0.283^2)} \\ F_{21}=1.094N \end{gathered}[/tex]
Now, we can calculate the net force for the y-axis:
[tex]\begin{gathered} F_y=0.759+1.094sin(45) \\ F_y=1.533 \end{gathered}[/tex]
Answer:
+ 1.533