## Physics (10th Edition)

F= $k\frac{|q_{1}q_{2}|}{r^{2}}$ Thus, we find: $k\frac{|q_{1}q_{2}|}{r^{2}}$= 1.5 N When the distance is reduced to one-ninth of its original value, F= $k\frac{|q_{1}q_{2}|}{(\frac{r}{9})^{2}}$= $k\frac{|q_{1}q_{2}|}{r^{2}} \times 9^{2}$ =$1.5 N\times81$ = 121.5 N