How does a Phytagoras Cup work?



How does a Phytagoras Cup work?

In: Physics

Enough water overflows the hole in the middle to trap the air in the bell shape. Gravity pulls the water down through the hole which makes the trapped air less dense than the outside air. That pulls the water in the cup up into the bell, and that little bit overflows which keeps the hole plugged. And since the hole empties out lower than the bottom of the cup, the suction keeps pulling water into the bell until it finally gets air from the cup.

When the liquid in a Pythagoras cup reaches high enough height to fall out the center, it creates a flow. As it falls down, it would create suction behind itself to prevent a vacuum forming. Because the channel is so narrow, that pulls more liquid from the bottom of the cup up and into the channel. This process continues until most of the liquid has poured out and air fills into the channel.