after valve is opened
initial state
Two connected balloons inflated to different sizes behave contrary to many students' expectations. Air from the smaller balloon goes into the larger one, increasing its size. This happens because the surface tension for the smaller balloon is greater than the surface tension of the larger one.
This home-made apparatus consists of a metal tube, a short clear plastic tube, and two valves. The balloons can be filled with air by connecting the plastic tube to the compressed air line in the auditorium.
Procedure:
Start with both valves open and both ballons deflated. Begin adding air until both ballons are approximately 5" in diameter.
Close the valve connecting balloons and continue adding air to the right balloon until its size becomes 3-4 times larger then the smaller one. Close the top valve.
Open the connecting valve. The smaller balloon will contract, forcing air inside the larger one.