PHY138 - Mechanics - Class 3 - Monday, September 18, 2006

Introduction

"If I have seen further than others, it is by standing on the shoulders of giants."

-- Newton

Announcements

The main Physics server had a catastrophic crash mid-afternoon on Tuesday
- Service was not restored until mid-morning on Friday, and some parts are still not restored
- Some of my email has been permanently lost!
The textbook store has run out of the standalone version of MasteringPhysics
- More are on the way
- The deadline for the first Pre-Class Quiz has been moved back to 10 AM Wednesday September 20
Pre-Class Quiz #2 on Chapters 5-6 is now released
- Due by 10 AM on Monday September 25
Tutorials begin this week
- Take your copy of the Student Workbook to every tutorial
- You will do a brief survey
  - If you answer all questions on the survey and register your clicker you will receive a bonus equal to one Pre-Class Quiz
Registering your clicker
- Go to http://www.iclicker.com/
- Choose Register**
- For Institution choose University of Toronto - St. George
- For Student ID enter your student number
- For Clicker ID enter the six-character code on the back of your clicker
- This must be completed by October 1
To find out where your tutorial meets:
- Go to STORM at http://www.storm.utoronto.ca/PHY138Y1Y/student/
  - Login: your student number
  - Password: your surname
    - Case sensitive: upper case and lower case letters count

Just For Fun

In §2.6 the text concentrates on Galileo's description of free fall, but also briefly mentions the Aristotelian approach to this physical circumstance. Another idea about falling is available via the button to the right. It will appear in a separate window.

Problem Solving

Although we will emphasise concepts on the tests and exam, there will be some conventional algebraic and/or numeric problems too. The text develops a problem-solving strategy, beginning with the box on page 24, which it uses for every worked example.

We have prepared a one-page document on a small variation of the strategy in the text. You may access a pdf version of it with the button to the right; separate window.

We will use this technique for every example we do in class, and strongly recommend that you use it for all problems that you do.

Today's Class

In-Class Questions

We asked three questions in class about significant figures. Here is a pdf of the questions we asked; separate window.

Most of the class got these questions correct( 80%, 80% and 75% respectively). The rest of the class should carefully review the material in §1.9: this subject is required for some MasteringPhysics problems.

As part of the discussion, we talked about how the potential amgibuity in these questions, particularly the second and third one, is resolved if one writes the numbers in scientific notation.

On Wednesday November 1, Dr. Harlow and I will re-visit this topic with significantly more sophistication than the text's discussion of this topic.

Other Class Materials

Here is a pdf of the PowerPoint on the SideScreens. Accessible via the blue button to the right; separate window.
We showed a Flash animation illustrating the difference between displacement and distance. Accessible via the blue button to the right; separate window.
We extended the textbook's Figure 1.22 (b) with this Flash animation This was the second extension to the text's discussion of Motion Diagrams in §1.6. It is intended to show the power of this visualisation technique.
Here is today's Journal in pdf format. A couple of students pointed out that I seem to have punched the wrong numbers on my calculator for the example. The corrected version appears in purple in the journal. Thanks to those students who pointed out the mistake.