Question

A point charge +Q is placed at the centroid of an equilateral triangle. When a second charge +Q is placed at a vertex of the triangle, the magnitude of the electrostatic force on the central charge is 8N. The magnitude of the net force on the force on the central charge when a third charge +Q is placed at another vertex of the triangle is

Answer 1

The magnitude of the net force of charge is 8N.

Solution:

The electrostatic force given by Coulomb's Law,

$F=\frac{k q_{1} q_{2}}{r^{2}}$

Now we are given the magnitudes of the two forces. We can figure out their directions and add the two forces to find the net force on the first particle. An equilateral triangle has angles of 60°, so the force will point at an angle of 30°.

$\mathrm{F}=8 \cos 30^{\circ} \mathrm{i}+8 \sin 30^{\circ} \mathrm{j}$

$= 4 \sqrt{3} i+4 j$

$F=\sqrt{(48+16)}$

F = 8 N