91影视

Figure is,

To determine the force at the$1\mathrm{nC}$charge, we must first determine the force at the positive and negative$2\mathrm{nC}$charges, which can be called$\mathrm{A}$, $\mathrm{B}$,and$\mathrm{C}$,respectively.

So, to urge the forces from charges and$\mathrm{C}$,

we use the approach indicated within the diagram to seek out the$\mathrm{x}$and$\mathrm{y}$components of them.

The y components eliminate out, as illustrated by the direction of the forces.

And need to place the $\mathrm{x}$components together (which is essentially just find the force of the particle so multiply it by the cosine of the angle ).

Answers are given as a magnitude and a direction by the force$\mathrm{F}$on the $1.0\mathrm{nC}$charge.

$\mathrm{F}=\mathrm{k}\frac{{\mathrm{q}}_1{\mathrm{q}}_2}{{\mathrm{r}}^2}$

${\mathrm{F}}_{\mathrm{A}鈫�\mathrm{B}}^{鈫�}={\mathrm{F}}_{\mathrm{A}鈫�\mathrm{B}}\mathrm{肠辞蝉胃}\hat{\mathrm{i}}+{{\mathrm{F}}^{鈫�}}_{\mathrm{A}鈫�\mathrm{B}}\stackrel{}{\sin }\mathrm{胃}\hat{\mathrm{j}}$

${\stackrel{鈫�}{\mathrm{F}}}_{\mathrm{A}鈫�\mathrm{C}}={{\mathrm{F}}^{鈫�}}_{\mathrm{A}鈫�\mathrm{C}}\mathrm{肠辞蝉胃}\hat{\mathrm{i}}-{{\mathrm{r}}^{鈫�}}_{\mathrm{A}鈫�\mathrm{B}}\mathrm{蝉颈苍胃}\hat{\mathrm{j}}$

${\stackrel{鈫�}{F}}_A={F^{鈫�}}_{A鈫�B}\stackrel{}{\cos 胃}\hat{i}+{F^{鈫�}}_{A鈫�C}\stackrel{}{\cos 胃\hat{i}}$

${\stackrel{鈫�}{\mathrm{F}}}_{\mathrm{A}}=\mathrm{k}\frac{\left(1脳{10}^{-9}\left(2脳{10}^{-9}\right)\right.}{(0.01{)}^2}\cos 60掳+\mathrm{k}\frac{\left(1脳{10}^{-9}\left(2脳{10}^{-9}\right)\right.}{(0.01{)}^2}\cos 60掳$

${\stackrel{鈫�}{\mathrm{F}}}_{\mathrm{A}}=1.789脳{10}^{-4}\mathrm{N}$