Center of Gravity on a Tightrope

Tami O'ConnorBy Tami G. O’Connor

When I taught second grade, one of our literature books was Mirette on the High Wire by Emily Arnold McCully.  I was that teacher who always taught thematically—that is, nothing ever was taught in a vacuum.  I tried as often as possible to tie things together.

Center of Gravity Lesson - Educational Innovations BlogSo as we read this book about a young French girl who learns from a retired high-wire artist to walk on a tightrope, in Language Arts we talked and wrote about our heroes, in Geography we researched where in the world France is.  And in Science, we learned about balance and center of gravity.

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The Bottle Balancer

Ron Perkins

by:  Ron Perkins

The bottle balancer is a fascinating conversation piece that illustrates the principle of center of gravity!  A small hole in an oak board allows you to balance a 2-liter soda bottle at an angle that appears to defy gravity. This can be used as a teaching tool or a centerpiece at your next party!  Hold the special angle cut of the wooden, bottle balancer board against a flat horizontal surface.   When a full, sealed, 2-Liter soda bottle is inserted into the wooden hole from above, it will catch the bottle flange and the wood/bottle assembly balances at a surprising angle.

Bottle Balancer

Explanation of Bottle Balancer:

In order for an object at rest to NOT tip over, its center of gravity, or its center of mass must be directly over its base. A goose-necked desk lamp is usually quite stable, unless it is configured so that the lamp part is stretched horizontally, far from the large base.  Then, it becomes less stable and often tips over.   The wood/bottle assembly example is more complicated than the lamp example because if the bottle is moved, the flowing liquid results in a change of its center of mass. Read the rest of this entry »