physics homework question

Question

Charges Q1 and Q2 exert repulsive forces of 18 N on each other. What

is the repulsive force in Newtons when their separation is decreased so

that their final separation is 73 % of their initial separation?

Answer 1

The force will increase since they are closer. The separation distance changes from d to 0.73d. Since the force varies inversely with distance squared, the final force will be (1 / 0.73)² times the initial force.