Objectives
1. Explain Newton's idea that the moon, like an apple, falls toward the Earth.
12.2 The Falling Earth
2. Explain why the moon does not fall into the Earth, nor the planets into the sun.
12.4 Newton's Law of Universal Gravitation
3. State Newton's law of universal gravitation.
4. Describe Cavendish's experiment to measure G.
12.5 Gravity and Distance: The Inverse-Square Law
5. Explain the significance of an inverse-square law.
12.6 Universal Gravitation
6. Explain the connection between gravitation and the idea that the universe may
stop expanding and begin to contract.
7. Give examples of how Newton's theory of gravitation affected the thinking
of philosophers of the eighteenth century.
Class Notes
8. Solve problems related to gravity.
Misconceptions
Note: The following statements are all FALSE!!!
1. Newton discovered gravity.
2. Above the atmosphere of the Earth there is no Earth gravity.
3. The moon and planets are beyond the pull of Earth gravity.
4. Gravity gets stronger with altitude, as evidenced by objects carried up a fligh of
stairs feeling heavier at the top.