The Physics of a "Wine Bottle in a Shoe"
In demonstrations, a cork can gradually slide out when the base of a wine bottle cushioned in a shoe is struck against a surface. The impact abruptly slows the bottle while the liquid inside continues moving; fluid oscillations and pressure waves can transmit force to the cork and start it moving outward.
Popular explanations call this “water hammer,” but more detailed discussions describe a complex interaction among liquid inertia, pressure waves, the gas space, and cork friction. It is not a guaranteed or safe method: the glass bottle may crack or shatter, and the cork may eject. This fact explains the phenomenon rather than recommending that anyone try the trick.