Universal Gravitation

Circular motion is not limited to objects on the earth. In fact, it was heavenly objects that first inspired questions about circular motion. Once it was realized that the moon orbits the Earth and that the Earth and the other planets orbit the sun, these heavenly circles had to be explained. Newton’s Law of Universal Gravitation describes the centripetal force necessary to accomplish these motions.

Essential Questions:

• What is Newton’s Law of Universal Gravitation, and what factors determine the strength of the gravitational force?
• How does universal gravitation relate to circular motion?