I enjoyed reading and studying the article by Padma Ganesh1 “Connecting Torque and Friction Using Tactile Learning Activities.” It reminded my of an old Johnny Carson routine where he used a simple stick to generate a whole series of jokes. The TPT article shows that much physics can be taught, learned, and demonstrated with a simple meterstick.

As an extension to the article, a pool cue can be used for the same “slip-stick” center of gravity (C.G.) determination. Guessing the location of the C.G. is a bit more problematic. When I did the experiment, the result did not agree with the theoretical C.G. for a right circular cone, which is ¼, the length as measured from the butt end. Then I realized that I had a truncated cone (frustum). Using the equation for the frustum, (see Fig. 1 at right) my experiment and theory agreed.

What surprised me was...

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