Answer:
[tex]F'=18/3=6\ units[/tex]
Explanation:
Electrostatic Force
We know particles 1 and 2 attract each other with an electrostatic force of 18 units. The force between two charged particles is given by Coulomb's formula
[tex]\displaystyle F=\frac{k\ q_1\ q_2}{r^2}[/tex]
Where [tex]q_1,\ q_2[/tex] are the charges and r is the distance between them.
We are told the new charge 2 is
[tex]q_2'=3q_2[/tex]
And the distance is three times the original
[tex]d'=3d[/tex]
The new force is
[tex]\displaystyle F'=\frac{k\ q_1\ (3q_2)}{(3r)^2}[/tex]
Operating
[tex]\displaystyle F'=\frac{3k\ q_1\ q_2}{9r^2}[/tex]
[tex]\displaystyle F'=\frac{k\ q_1\ q_2}{3r^2}[/tex]
This force is one third of the other one, so
[tex]\boxed{F'=18/3=6\ units}[/tex]
