Centre of mass experiment
Some science fun in the office today - a centre of gravity/centre of mass experiment.
Try it yourself - leave around 100ml in the can and then balance it diagonally.
When the can is empty the centre of mass is somewhere in the centre of the can. However, when there is a little bit of liquid in it, the centre of mass moves towards wherever the liquid is. So when the can is diagonal, gravity pulls the water towards the bottom and allow the centre of mass to be supported.