# What is the force, in terms of Coulomb's constant, between two electrical charges of 1 C and -9 C that are 9 m  apart?

$F = k \frac{| {q}_{1} | | {q}_{2} |}{r} ^ 2 \setminus q \quad \setminus \rightarrow \frac{F}{k} = \frac{| {q}_{1} | | {q}_{2} |}{r} ^ 2$
q_1 = 1C; \qquad q_2=-9C; \qquad r=9m.