A platform is placed on top of an air-filled bellows that is about the size of a bathroom scale (say, 1ft x 1ft x a few inches tall). A small (~1in) tube connects to the bellows at one side, and rises up vertically. The other end of the tube is open to the atmosphere. A man of average height and weight arrives. He notices that the open end of the tube is about at eye level. The man steps onto the platform and the bellows completely collapses since the air from inside is expelled through the tube, which is the only path for it to escape. After the man steps off the platform the bellows refills with air, by virtue of the tube.

The bellows is then filled with water (all air is removed). The man again steps onto the platform. How much water is expelled from the bellows?

The man’s identical twin comes along and joins his brother on the platform. How much more water is expelled?