# PHY138Y - Mechanics - Class 6- Wednesday Sept. 24, 2003

## Introduction

The painting is of Newton, by William Blake (1805). The original is in the Tate Museum in London, England.

### PHY138 Representative Assemblies

This week we meet with the Representatives from Thursday's tutorials.

### Yom Kippur

Yom Kippur is Monday, October 6. This will be our 9th class, and many of our Jewish students will be unable to attend. Thus for this class I will make a particular effort to follow the textbook.

## Just for Fun

 You may have noticed that in Monday's class the Departmental photographer, Raul Cunha, was taking some pictures. I have selected five of them into a "photo album" which you may access by clicking the button to the right. It will appear in a separate window.

## Today's Class

 Note: we have changed the Textbook Reference which I posted in the summary for Class 2. We are now including §3.6 - Relative Velocity .
 We went back and discussed §3.5 - Tangential and Radial Acceleration. Next we discussed the material in §3.6 - Relative Velocity; this did not follow the text very closely. At the end we showed a Flash animation of different reference frames, using an example by Galileo. You may access the animation by clicking on the button to the right. Separate window; 22k.

As part of our review of Newton's laws of motion, I showed a nearly identical statement of the first law from China that preceded Newton by over 1300 years.

"The cessation of motion is due to the opposing force ... If there is no opposing force ... the motion will never stop."

-- Mo Ching ("Pulse Classic") circa 300 AD

 We discussed §4.3 - Inertial Mass and §4.5 - The Gravitational Force and Weight more-or-less together. A small html document on the way we discussed inertial and gravitational mass may be accessed by clicking on the button to the right. Separate window; 10k. We then discussed §4.6 - Newton's Third Law. We discussed an example: the ballistocardiogram (BCG). You may access a small html document on BCG's by clicking on the button to the right. Separate window; 52k. You may access the "Journal" from today's class by clicking on the button to the right. Separate window; 195k.