Here is a video from the “‘Rotational buoyancy’ – Hydrostatic pressure in solid body rotation” demonstration. The GIF is a little hazy but clearly shows the cork staying centrally located under rotation and the marble being pushed to the end of the jar (and up next to the lid). The full video is here.
An index of all the demonstrations posted on this blog can be found here. Don’t forget to follow @nbkaye on twitter for updates to this blog. If you have a demonstration that you use in class that you would like to share on this blog please email me (firstname.lastname@example.org). I also welcome comments (through the comments section or via email) on improving the demonstrations.