Physics Honors/AP 1 and 2

Homework

# Physics Chapter 5: 8-10 Kepler's Laws

## Homework

Text Reading: Giancoli, Physics - Principles with Applications, Chapter 5: 8-10

##### Study Points
• 5.8 Kepler's laws were empirical: they describe, but cannot explain, a particular phenomena. Newton's laws are considered explanations because they identify universal characteristics of matter and relationships of moving objects based on those characteristics.
• 5.9 The Moon rises an hour later each day because not only is the Moon revolving around the Earth, but the Earth is also revolving around the Sun. Lunar phases are relative to the Sun's position, so the Moon must not only revolve around the Earth, but it must catch up to the Earth's changed position relative to the Sun each day.
• 5.10 Only four natural forces are known: gravity, electromagnetic force, and the weak and strong nuclear forces that operate within the nucleus of the atom. We spend most of the first part of the course talking about gravity, which has only one direction (attractive). Next semester we'll talk a lot about the electromagnetic force, which is more complicated (it operates in both attractive and repulsive modes, with one or more poles of reference).
• Section 9: Kepler's laws were empirical: they describe, but cannot explain, a particular phenomena. Newton's laws are considered explanations because they identify universal characteristics of matter and relationships of moving objects based on those characteristics.
• Section 10: Only four natural forces are known: gravity, electromagnetic force, and the weak and strong nuclear forces that operate within the nucleus of the atom. We spend most of the first part of the course talking about gravity, which has only one direction (attractive). Next semester we'll talk a lot about the electromagnetic force, which is more complicated (it operates in both attractive and repulsive modes, with one or more poles of reference).

### Key Equations

Newtonian form of Kepler's equation:

### Web Lecture

Read the following weblecture before chat: Kepler and Newton

### Study Activity

Working with Gravity and Orbits.

Change the mass of the Earth and Sun to determine how Earth's orbit is affected. How long is the Earth's period if the Sun's mass is 1.5 times its current mass? Does changing the Earth's mass to 1.5ME change the period as much? more? less? Why?

### Chat Preparation Activities

• Forum question: The Moodle forum for the session will assign a specific study question for you to prepare for chat. You need to read this question and post your answer before chat starts for this session.
• Mastery Exercise: The Moodle Mastery exercise for the chapter will contain sections related to our chat topic. Try to complete these before the chat starts, so that you can ask questions.

### Chapter Quiz

• Required: Complete the Mastery exercise with a passing score of 85% or better.
• Go to the Moodle and take the quiz for this chat session to see how much you already know about astronomy!

### Lab Work

If you want lab credit for this course, you must complete at least 12 labs (honors course) or 18 labs (AP students). One or more lab exercises are posted for each chapter as part of the homework assignment. We will be reviewing lab work at regular intervals, so do not get behind!