# PHY138Y - Mechanics - Class 12 - Monday October 24, 2005

## Introduction

Robert Hooke was working on the same problem as Newton at the same time: what is the relationship between forces, masses, accelerations and gravity. They were bitter rivals. Here is a fragment of a statement by Newton about Hooke:

“This carriage towards me is very strange & undeserved, so that I cannot forbeare in stating that point of justice to tell you further … he should rather have excused himself by reason of his inability. For tis plain by his words he knew not how to go about it.”

Newton won the competition, and today we tend to only remember Hooke for his discovery about the relation between the force a spring exerts on an object and how much the spring is stretched. If you are interested, you can learn more about this remarkable man at http://www.ucmp.berkeley.edu/history/hooke.html.

## Coming Up

• This week: finish Chapter 11 Work and discuss Chapter 13 Rotation of Rigid Bodies
• Monday October 31: review for the test
• This will be 100% PowerPoint based
• A pdf of the PowerPoint slides will be released on Wednesday
• Tuesday November 1, 6:00 - 7:30 PM: Test #1
• You must bring your student card
• The test is closed book
• You may bring a single 8 1/2 by 11 inch sheet of paper on which you have written anything that you wish
• You may bring a calculator without text storage or communication capabilities
• There will be 8 Multiple-Choice questions worth 8 marks each and 1 Long Answer question of 6 parts worth a total of 36 marks
• Wednesday November 2: Dr. Harlow and I will discuss a laboratory topic: Error Analysis
• Monday November 7: the Waves section of PHY138 begins with Dr. Harlow

## Syllabus Changes

In order to have time to discuss the other material of Chapter 13 carefully, I have dropped one of my favorite topics from the syllabus: §13.8 - Rolling Motion. I have also added the Angular Velocity Vector sub-section of §13.9; the rest of this section continues to be deleted from the syllabus. Both the Mechanics Home Page and the pdf version of the syllabus have been updated to reflect these changes.

## Today's Class

We finiished Chapter 11, discussed an application of Power - Basal Metabolism, and then began Chapter 13. We largely finished our discussion through §13.4.

 Dr Harlow pointed out after class that I wrote "line of action" instead of "moment arm" when discussing how to calculate the torque. The journal has been corrected in purple.

## Supplementary Notes

 We discussed the Basal Metabolic Rate in class. Supplementary Notes on this topic in html format are available.