1. February 10, 2012 Physics Mr. Payne

2. Multiple Choice Answers

3. Short AnswerQuestion 10 • Discuss the following statement: “A satellite is continually in free fall.” • Answer • A satellite in a circular orbit around Earth moves like a projectile. One component of its motion is parallel to Earth’s surface, while the other component is a free-fall acceleration toward Earth. The horizontal component of the motion is just the right magnitude for Earth’s curved surface to fall away at the same rate as the satellite’s free-fall acceleration.

4. Short AnswerQuestion 11 • Earth exerts a 1.0 N gravitational force on an apple. • Does the apple accelerate toward Earth, or does Earth accelerate toward the apple? Explain your answer. • Answer • They both accelerate toward each other. Earth’s acceleration is extremely small compared to that of the apple because Earth has a much greater mass than the apple does.

5. Short AnswerQuestions 12 and 13 • Earth exerts a 1.0 N gravitational force on an apple. • What is the magnitude of the gravitational force the apple exerts on Earth? • Answer: 1.0 N • What is Earth’s weight in the apple’s gravitational field? • Answer: 1.0 N

6. Short answerquestions 14 and 15 • Briefly, how did Ptolemy describe the motion of the planets? • ANSWER: • Ptolemy described the planets moving in small circles called epicycles while simultaneously moving in larger circles around Earth. • Briefly, how did Copernicus describe the motion of the planets? • ANSWER: • Copernicus described the planets, including Earth, moving in circular orbits around the sun.

7. Short Answerquestion 16 • According to the big bang theory, what occurred in the brief instant after the big bang? • ANSWER: • The four fundamental interactions of physics operated in a unified manner. The high temperatures and energy caused all particles and energy to be indistinguishable.

8. PROBLEMS

9. Big bang theory • Review pages 936-942 from the textbook. • Be able to describe in general terms the history and possible fates of the Universe. Know the four fundamental forces, and when they separated from their common beginning.