If my dad were alive he’d likely make me do some math on this. NPR has a great piece on how to get that pesky ketchup out of the glass bottle, and why it’s such a pain in the neck. The root of the issue? Newtonian physics:
Ketchup, Zaidan says in the video, is a pretty unusual substance. It behaves both like a solid and a liquid, depending on how you shake that bottle.
That’s because there are two types of fluid: Newtonian and non-Newtonian. Newtonian fluids retain their viscosity — or resistance to flow — regardless of the amount of force you put on them. Non-Newtonian fluids are what Zaidan calls “rule breakers.” Their thickness and viscosity change based on how long, how hard and how fast you push.
It’s pretty fascinating, check it out. Me? I’m all for the squeeze bottles, initial watery shot and all.