The test tube can be used particularly easily as a hollow body filled with water and air, i.e. as a Cartesian diver. A mark indicates the level up to which the test tube must first be filled with water. If you then hold it up with your finger, turn it 180 ° and then put it into the appropriate water container, the air remaining in the diver ensures adequate buoyancy. A reinforcement of the test tube opening ensures, on the one hand, a stabilization of the swimming position and, on the other hand, protects the diver when he hits the bottom.
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.jpg "Preview: Cartesian diver")
.jpg "Cartesian diver")
