A balloon rubbed against denim gains a charge of −7.0 µc. what is the electric force between the balloon and the denim when the two are separated by a distance of 3.0 cm? (assume that the charges are located at a point.) the value of the coulomb constant is 8.98755 × 109 n · m 2 /c 2 . include direction of the force. answer in units of n.