Frozen Against Gravity
Emmett Witmer
Award: Top 100
Award: Honorable Mention for Procedures
School: sleepy hollow high school
Teacher: leila madani
Category: Contrived
Photo #21095
Frozen Against Gravity
This photo shows a cocktail ice cube suspended by a salted string running along its surface. I created this by placing a string on top of an ice cube and sprinkling salt over it, causing the string to cling to the ice. The melting point of water is lowered compared to pure ice due to dissolved salt ions disrupting the solid structure. The salt dissolving on the ice is an endothermic process, so it absorbs heat from the surrounding ice and air, lowering their temperatures and briefly melting the surface.
To undergo this phase change, the ice must absorb heat energy from its surroundings, which causes localized cooling. As the melted ice-salt water spreads out, it becomes more diluted, raising its freezing point. The surrounding ice, now much colder from losing heat, is cold enough to refreeze this diluted solution around the string. As this refreezing occurs, the string becomes embedded in the ice.
When the string bonds to the ice, intermolecular forces between the materials collectively exceed the force of gravity pulling downward. This allows the cube to be lifted, showing that electromagnetic interactions can dominate over gravity at our macro scales.
The cube itself also demonstrates optical effects. Light passing through smooth faces refracts, bending toward the normal as it enters and away as it exits, making the background image appear compressed. Textured sides scatter light, producing the bright highlights and reflections you see on the sides of the cube.
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