Problem 13.17

จาก \(\vec{F} = \vec{F}_{+}+ \vec{F}_{-}\)

r̂r̂

\(\vec{F} =\frac{kqQ}{r^{2}}_{+}+\frac{k(-q)Q}{r^{2}}_{-}\)

îĵ

\(\vec{F} =\frac{kqQ}{r^{2}}(\cos (60º) + \sin (60º) )\)

îĵ

\(+\frac{k(-q)Q}{r^{2}}(-\cos (60º) + \sin (60º) )\)

î

\(\vec{F} =\frac{2kqQcos(60º)}{r^{2}}\)

î

\(\vec{F} =\frac{kqQ}{r^{2}}\)

\(|\vec{F}| =\frac{kqQ}{r^{2}}\;\blacksquare\)