in an experiment using Coulomb's apparatus, a sphere with a charge of 3.6 x 10^-8 C is 1.4 cm from a second sphere of unknown charge. The force between the spheres is 2.7 x 10^-2 N. What is the charge of the second sphere?

Question

I get 1.3 x 10^-4 C, but the answer is supposed to be 1.6 x 10^-8. Any possibility the book has a misprint? Where did I go wrong?

Answer 1

F = k Q1 Q2/r^2
k = 9*10^9

2.7 * 10^-2 = 9 * 10^9 * 3.6 * 10^-8 Q2/.014^2

Q2 = 1.63 * 10^-5 * 10^-3
= 1.63*10^-8 C