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Pascal'S Law - Coiled Tube Paradox


To illustrate Pascal's law in a dramatic way.


Mounted short plastic tube with green water, three-turn tygon tube mounted on plastic cylinder.

Setup Time

5 min.




Referring to the photograph on the right, pouring water (colored green) into the tube at the left causes the asymmetric configuration shown due to the equalization of pressure in the central air bubble. Similarly, if one end of a three-turn loop of tubing is raised vertically, water poured into the high end will never come out the bottom end, even when the bottom end is lying flat on the table. ◙


A. A. Bartlett and Robert Stoller, The paradoxical manometer, TPT 19, 41-42 (1981). Father John Milton and Ellen Springer, Doing Physics: Walkway forces and Physics phun ideas, TPT 20, 328-32

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