Question

Find the electrostatic force between charges of -2.0 C and +5.0C separated by a distance of 75m in a vacuum.

Answer 1

Given:

$q_1=-2.0\:\rm C$

$q_2=5.0\:\rm C$

$r=75\:\rm m$

The Coulomb's law says

$$F=k\frac{|q_1||q_2|}{r^2}$$

$$F=9*10^9\frac{2.0*5.0}{75^2}=1.6*10^7 \:\rm N$$

The force is attraction.