UNIVERSITY PHYSICS I CHAPTER 6 Gravitational force and Gravitational Field 86.1 The gravitational force 1. How did Newton deduce the gravitational force lay Every particle in the <Y Moon universe attracts every 中a other particle with a force directly proportional to the product of their masses and inversely proportional to the square of the distance between them The direction Earth of the force is along the line joining the particles.1 1. How did Newton deduce the gravitational force law Every particle in the universe attracts every other particle with a force directly proportional to the product of their masses and inversely proportional to the square of the distance between them.The direction of the force is along the line joining the particles. §6.1 The gravitational force