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When you mix cornstarch and water in a bit under a 2:1 ratio, you get oobleck, a substance with some odd physical properties. This is a great kitchen science experiment everyone should try at least once.
At low speeds, oobleck behaves like a liquid. If you gently swish your fingers in a bowl of it, it feels like milk or heavy cream. However, if you make a fist and punch the surface, your hand bounces off with a thud—it’s like hitting a slab of raw meat.
If you vibrate oobleck, even stranger things happen.