Thursday, April 14, 2011

Thurs-Demo: The one with all my marbles

Quick demo today showing off the porosity of a container full of small marbles and another container of larger marbles. So I ask you: which container will hold more water: the container filled with small marbles, or the container filled with large marbles? Why? Be sure to state your answer before watching the demo:

Porosity in Differently Sized Media from Matt Kuchta on Vimeo.

It may seem surprising that the containers each held the same amount of water. Think about it this way: there are big pores between big marbles and there are smaller pores between small marbles. There are fewer big marbles in the container, therefore fewer pores. You can even answer the question mathematically - regardless of diameter, a sufficiently large container of identical spheres (packed as closely together as possible) will always have the same ratio of empty space to filled space.

Just a quickie right now though. I had the day that ended up being over 9 straight hours of lectures and meetings. My brain is mushy.


  1. Very nice! My wife wants to know if you were trained as a magician. Seriously. Very nice technique. And good science, too!

  2. No magician training, just off-balance tendencies when it comes to demos.