PHY138 - Mechanics - Class 5 - Monday, September 25, 2006

Introduction

"Nature and nature's laws lay hid in night;
God said 'Let Newton be' and all was light."

Alexander Pope, epitaph intended for Sir Isaac Newton

Today's Class

Today we discussed Chapter 4 and came within a whisker of finishing our discussion of Chapter 5.

In-Class Questions

We asked two questions in class today. A pdf of them is available via the button to the right; separate window.

Question About Forms of Newton's 2nd Law

Here are the distribution of answers given by the class. In-class discussion did not change the distribution significantly. Almost half the class did not believe the official position that answer A is in fact correct. Therefore we discussed this in class.

Question About "From the Earth to the Moon"

Here is the distribution of answers to this question. Although C is correct, about 40% of the class got it wrong. If you are among the 40%, I advise you to think more carefully about weight, acceleration, etc. and perhaps carefully re-read §5.3 of the text.

Other Class Materials

Here is a pdf of the PowerPoint used on the side screens.
And here is today's Journal.

Suggested Problems

• Chapter 4: 12, 13, 14, 28, 50
• Chapter 5: 25, 26, 31, 33, 70

The arrows let you jump to the previous/next class summaries.