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The Kid Should See This

Why is ketchup so hard to pour?

That moment that ketchup transitions from a solid, high up in the ketchup bottle, to a liquid that squirts all over your fries – that moment is a big physics moment. Why? Ketchup is a non-Newtonian fluid (like oobleck, peanut butter, custard, toothpaste, paint, blood, or quicksand) that can switch between a solid and liquid state, and ketchup is non-Newtonian in two different ways…

In that transition moment, ketchup may be responding to a strong, quick force, suddenly making it thinner, or if you’re patient and apply just a wee bit of force, it may start flowing given some time and gravity. Grab a ketchup bottle and get the details in this TED Ed lesson by George Zaidan, with animation by TOGETHER.

Related watching: oobleck, TED Ed, the incredible physics of ants, and more about that sugar in your ketchup.

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