Gravitational Force (College Board AP® Physics 1: Algebra-Based): Study Guide

The gravitational force between two objects or systems is attractive

• An attractive force is a force that pulls objects together

There is a universal force of attraction between all matter with mass

• The gravitational force is always exerted along the line connecting the centers of mass of the two interacting systems

• The gravitational force on a system can be considered to be exerted on the system’s center of mass

Gravitational force has an infinite range, meaning it affects all objects in the universe

• There is a greater gravitational force around objects with a large mass (such as planets)

• There is a smaller gravitational force around objects with a small mass (almost negligible for atoms)

The Earth's gravitational force is the centripetal force that keeps the Moon in a circular orbit around the Earth

The relative position between the centers of mass of two systems can change due to:

• one or both objects rotating around the other

• one or both objects moving away from each other

When the relative position of the centers of mass changes but the change in the gravitational force is negligible, then the gravitational force is considered constant

• The gravitational force is considered constant at all points between the initial and final positions of the systems

The separation distance between the initial and final positions of the systems has to be very small to create a negligible change in the gravitational force between them