PHY138Y - Mechanics - Class 12 - Monday October 23, 2006


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

Today's Class

We finished Chapter 11 by discussing power. We then did an application of this idea in discussing metatolbic rates. Next we began our discussion of Chapter 13 - Rotation of a Rigid Body. This is the final chapter for the Mechanics section of PHY138, and we will continue our discussion next class.

Supplementary Notes

Supplementary Notes on metabolic rates in html format are available. Basal Metabolism notes

In-Class Questions

Here are the clicker questions we asked today

The Most Effective Arrangement of the Wrench and Rod

About 70% of you got this correct: B.

The Least Effective Arrangement

You collectively did even better on this one. Over 80% correctly answered C.

Other Class Materials

Pdf version of the PowerPoint on the side screens. Theory of Intelligent Falling
Today's Journal. Theory of Intelligent Falling

Suggested Problems

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