9.2. Newton’s Universal Law of Gravity http://www.ck12.org
9.2 Newton’s Universal Law of Gravity
Objectives
The student will:
- Understand Newton’s Universal Law of Gravity.
- Use Newton’s Universal Law to solve problems.
Vocabulary
- eccentricity
- empirical
Introduction
Humanity has always known that objects fall to the ground, but for many years, no one understood why gravity
works. A key breakthrough came from the work of Isaac Newton (1642-1727), (Figure9.5). In 1687, Newton
published his most important book,Philosophiæ Naturalis Principia Mathematica, which connected the falling of
objects on Earth with the motion of the planets. Prior to his book, those two concepts were thought to be completely
unrelated.
FIGURE 9.5
Isaac Newton.The possibility that gravity extended beyond the Earth first occurred to Newton in 1666. According to his personal
accounts, he watched an apple fall from a tree and wondered if the same force that acted upon the apple also acted