We use Coulomb’s Law and Newton’s Second Law to determine the acceleration of charge q.• The force on q due to Q is$F = \; \frac{kQq}{r^2}$• Acceleration is given by:$a = \; \frac{kQq}{mr^2}$This means that acceleration varies inversely with $r^2$. The correct graph should show a decreasing function of r with a sharp drop.