Question

the electrostatic force between two objects is 40N. if the charge of one object is cut in half, and the distance is doubled, what is the new force?

Answer 1

F1 = K Q1 Q2 / R1^2

F2 = K Q1 / 2 * Q2 / (2 R1)^2

F2 / F1 = 1/2 / 4 = 1/8

The new force is 5N (1/2 due to charge and 1/4 due to distance)