Question

Two balloons are charged with a different quantity of charge: balloon A with 5 nC and balloon B with 4 nC. They are held apart at a separation distance of 3.5 meters. Determine the magnitude of the electrical force of repulsion between them.

Answer 1

Given:

$q_1=5*10^{-9}\:\rm C$

$q_2=4*10^{-9}\:\rm C$

$r=3.5\:\rm m$

The Coulomb's law says

$$F=k\frac{|q_1||q_2|}{r^2}$$ $$F=9*10^9*\frac{5*10^{-9}*4*10^{-9}}{3.5^2}=1.47*10^{-8} \:\rm N$$