SAT Subject Physics Practice Question 357: Answer and Explanation
53. A pair of a particles (helium nuclei) approach one another head on. Compared to the force they exert on one another at a distance of .066 m, by how much will the force the two particles exert on one another at .033 mm increase?
Correct Answer: C
The correct answer is (C). According to Coulomb's law, the force exerted by two charged bodies on one another is indirectly related to the square of the distance between them. When the distance is halved, they exert four times more force on one another.