285sions on a sliding (Vernier) scale matching the same width as nine divisions on a fixed scale parallel with it. The result is that each division on the Vernier scale is 90 times amplified compared to the actual distance it's measuring. 2 This is quite a significant "zooming-in" effect and can thus allow even typically "rough" tactile methods, such as used by the blind, to detect very tiny distances with high resolution. See the box below for a more detailed explanation.As a starting point, STEP 1 (see photo sequence in Figs. 1-5), we used the plastic Brailled tactile centimeter rule as a fixed scale and clamped it down onto the lab table. We then clamped a scrap piece of door stop molding so that it butted perpendicularly against the left end of the tactile fixed scale to serve as a stop. A carpenter's square was used to make sure they were square.In STEP 2, we placed the item to be measured, such as the aluminum cylinder shown, against the wooden stop at
Brain-teasing torque demos are a part of every physics teacher’s repertoire. I can thank Ted Foster of Cal Poly, San Luis Obispo, for my personal favorite, the “torque rack.”
A homemade pitching machine that launches plastic holey balls can be constructed from drill motors and sanding disks. This could possibly find uses in the physics classroom.
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