Demos: 2A-09 Two Balloon Surprise
Two identical balloons are inflated different amounts and connected by plastic tubing which contains a valve. What happens when the valve is opened? The larger balloon will grow larger and the smaller balloon will deflate. What happens is that fluids will flow from high pressure regions to low pressure regions. It happens that the air in the smaller balloon is under greater pressure than the air in the larger balloon. Consequently, the air will flow out of the smaller balloon (a relative high pressure region) into the larger balloon (a relative low pressure region).
Directions for doing the demo: Inflate one balloon and partially inflate the other. Place stoppers in the balloons and connect the balloons by the plastic tubing and valve. When assembled, turn the valve and watch what happens.
Suggestions for Presentation: Counterintuitive demonstration, discuss the concept of pressure and relate to the students how it is more difficult to start blowing up a balloon as compared to blowing into a partially inflated balloon.
Applications: Pressure, Hooke's Law, Flow of Fluids from High Pressure Regions to Low Pressure regions