These mesmerizing GIFs of Jell-O falling, flattening, then bouncing back has been making the rounds of the Internet today. The original post, from the FreshPhotons Tumblr, has been re-blogged more than 3,000 times.
These images may have you saying WTF, but really you should be asking WTP — P for physics. Watch the gelatin bounce, then read our explanation of the how and why behind gelatin’s jiggle below:
The video came from ModernistCuisine YouTube Channel, taken at 6200 frames per second. They probably didn’t use actual Jell-O, since the film says gelatin but the desserts properties are similar:
The amazing physics of this fruity desert come from its chemical make up. Originally gelatin is a flavorless protein, isolated originally from animal by-products but also found in seaweed. It gives the desert its wiggly texture.
So… Is it a solid or a liquid? Actually.. it’s neither. It’s a colloid gel because it is actually liquid suspended in a matrix of solids.
When the gelatin is heated up with water, sugar, and flavorings, it protein loses its shape and dissolves into the liquids. But, as it cools down, the protein falls out of solution and solidifies into a matrix of strands of protein and which trap the liquids into a solid-looking shape called a colloidal gel, according to a post from the Department of Physics at the University of Illinois at Urbana Champaign.
These physical properties give the Jell-O a very high elastic limit — the point where the solid stops bouncing back from being deformed. That makes the squares of Jell-O bounce back to their original shape without breaking.
When you warm the Jello-O up again, by putting it in your body, it dissolves back into the water and turns liquid again. Boxed Jell-O has added flavorings and sugar, which interferes with the gelatin’s ability to congeal, so it is typically softer than pure gelatin would be.
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