OpenStax College Physics for AP® Courses, Chapter 18, Problem 36 (Test Prep for AP® Courses)

This is College Physics Answers with Shaun Dychko. We are going to find the force between two particles that each have a charge of 3.2 times 10 to the minus 19 coulombs when they are separated by 5 centimeters— 5 centimeters is 5 times 10 to the minus 2 meters— and then we'll plug into this formula, which says the force between these two charges is the Coulomb's constant times each of the charges multiplied together but it's just one charge q squared— in this case because the charges are the same— divided by the distance between them squared. So that's Coulomb's constant times 3.2 times 10 to the minus 19 coulombs squared divided by 5 times 10 to the minus 2 meters squared and that is 3.7 times 10 to the minus 25 newtons. It's possible we should have just one significant figure since our distance has one significant figure but anyway... I wrote 3.7 in any case.