Ever-Present Center of Gravity

By Jane K. Priewe

Everything has a center of gravity, and once you’ve found that point, any object can be balanced. A ruler will balance across your finger at the six-inch mark. A table fork will balance on your finger somewhere near the narrowest part of the handle. A book will balance on your head, if placed properly. That point where something will rest without falling off is called its center of gravity.

Here is a balancing trick where seeing is believing!

1. Poke a 4″ (10 cm) nail into the small end of a large cork.

2. Directly opposite each other, and a trifle closer to the cork’s small end than to its larger end, stick two identical forks with their handles angling in the same direction as the nail’s head.

3. Moving the nail slowly along the rim of a jar or glass, you will discover a point where the forks balance!

The fork handles may not be parallel to the tabletop when you find the cork-fork-nail object’s balancing point, but its center of gravity is the place on the nail where it rests on the jar’s edge without falling off.