Fast-moving cornstarch acts like a liquid before hardening

If you mix cornstarch and water, you will have a substance that defies common sense. If you punch it with your first, it will feel like you hit a solid wall. But if you move your finger through it slowly, the substance will flow like honey. And scientists have long struggled to understand how this transition happens.

A new study in Physical Review Letters has figured it out using high-speed photography and direct force measurements. The authors, from the University of Minnesota, reported that at an extreme speed, the cornstarch mixture behaves like a liquid first before becoming tougher.