An electrostatic force of 81N exist between a charge of + 2 x 10-5C and a second charge of + 4.5 x 10-4C. What is the distance between the two charges? Is it attractive or repulsive?

Coulomb's law states that F = k (q1) (q2) / r^2, where k = 9 x 10^9 N-m^2/C^2

From the given:

81 = (9x10^9) (2x10^-5) (4.5x10^-4) / r^2

r^2 = 1

r = 1 m

Since both charges have the same sign (positive), the force is repulsive (like charges repel).

Therefore there is a 1-m distance between the two charges, and the force is repulsive.