Physics

Why is it so hard to pour ketchup from a bottle?

Ever go to pour ketchup on your fries…and nothing comes out? Or the opposite happens, and your plate is suddenly swimming in a sea of red?

This excellent TED-ED talk by George Zaidan describes the physics behind this frustrating phenomenon, explaining how ketchup and other non-Newtonian fluids can suddenly transition from solid to liquid and back again.