Question

One object has a charge of +5.0 · 10-6 c, and a second object has a charge of +2.0 · 10-6

Answer 1

The electrostatic force between two charged objects is given by
$F=k \frac{q_1 q_2}{r^2}$
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:
$q_1=+5.0 \cdot 10^{-6} C$
$q_2 = +2.0 \cdot 10^{-6} C$
$r=0.5 m$
So if we plug these numbers into the equation, we can find the electrostatic force between the two objects:
$F=(8.99 \cdot 10^9 Nm^2C^{-2}) \frac{(5.0 \cdot 10^{-6} C)(2.0 \cdot 10^{-6}C)}{(0.5 m)^2}=0.36 N$