The electrostatic force between two charged objects is given by
[tex]F=k \frac{q_1 q_2}{r^2} [/tex]
where
k is the Coulomb's constant
q1 is the charge of the first object
q2 is the charge of the second object
r is the separation between the two objects
In our problem:
[tex]q_1=+5.0 \cdot 10^{-6} C[/tex]
[tex]q_2 = +2.0 \cdot 10^{-6} C[/tex]
[tex]r=0.5 m[/tex]
So if we plug these numbers into the equation, we can find the electrostatic force between the two objects:
[tex]F=(8.99 \cdot 10^9 Nm^2C^{-2}) \frac{(5.0 \cdot 10^{-6} C)(2.0 \cdot 10^{-6}C)}{(0.5 m)^2}=0.36 N [/tex]
