Hydrostatics Floating Test Tube The Cartesian diver consists of a small figurine of glass or ceramic just floating in water inside a tube, bottle, or other container. When the lid of the container is pressed, the diver sinks to the bottom. You can make your own, as we describe here. An inverted glass test tube floats in water if there's enough air trapped inside. Obtain a large jar, half-full of water, and float an inverted test tube in the water with just enough water rising in the tube so that the tube floats as shown. Close the top of the jar with a flexible rubber sheet so it makes an airtight seal. What will happen if we press the rubber sheet inward so that the volume inside the jar is reduced? The test tube will rise up a bit with respect to the water level inside. The test tube will sink a bit with respect to the water level inside. The test tube will neither rise nor sink with respect to the water level inside. plzz explian this!!!!!!!!!!!!!!!