Centrifugal force

Comic from: http://xkcd.com/123/

Wei did something extraordinary and unbelievable today.  Before starting our Sunday Buddhist class this morning, and Wei helped to get a small pail of water to clean up the bookshelves in his class.   Halfway walking through the corridor, he asked me to hold the rag, and said: "Mom, I will show you magic."
There and then he started to swing his pail of water round, wanting to show me some physics law of centripetal and centrifugal force, where the water was supposed to stay in the pail.
And you know what happened, half the water spilled into the corridor hallway, and I was staring at Wei in disbelief.  Wah, I was so mad, how could he do this? I started to scold him, and quickly got a mop to mop off the mess, while he returned to the class.
Thinking back now, and telling J about it, we both laughed and laughed.  I should have taken a picture of Wei in action, swinging the pail.  Obviously he didn't swing it fast enough and didn't have the sense to try the swinging in the bathroom instead of the corridor.