In this classic science experiment, water completely refuses to fall out of an upside down glass. When you place a piece of fine window screen or mesh over an open jar filled with water, invert it, and remove your hand, something astonishing happens: not a single drop spills.
This counterintuitive trick works because of surface tension and atmospheric pressure. Water molecules are polar and cling tightly to one another, a property known as cohesion. When water encounters the tiny holes of the mesh screen, the cohesion creates a thin elastic skin across each individual opening. This skin forms tiny curved barriers called menisci.
At the same time, air pressure outside the container presses upward against that membrane of water. Because air cannot push inside through the sealed mesh to displace the liquid, the water stays trapped firmly inside the jar. If you tilt the jar slightly, air rushes into the top, breaks the surface tension, and the water immediately dumps out.
It is a simple tabletop demonstration that reveals the immense strength of micro scale forces acting against gravity. Have you ever tried this experiment at home?
#scienceexperiments #physics #surfacetension #sciencetricks #stem #learnontiktok #coolscience #diyexperiments
Disclaimer: This video is for informational and educational purposes. The story is drawn from public scientific records, and accompanying images illustrate the concept.
