60. Effects in a Vacuum

A bell jar with several demonstrations is evacuated in class:

1. A balloon with a tiny amount of air inflates.
2. A metal ball of air is balanced with a mass (shown below). As the bell jar is evacuated, the buoyant force decreases and the ball falls raising the mass.
3. A short mercury column with a small air bubble falls.
4. A container of water boils at room temperature. The water temperature as measured by a thermometer falls rapidly.