I'm modelling a series of objects with some physics and mathematics and I found interesting to talk about the library I am using: Delphi APE. This fantastic library available for Delphi (Windows) and Lazarus (Linux) allows very simple task as powerful as gravity, collision processes, grouping behaviour and general process. Great the job done by Alex cove and others like Vincent and Jeremy who helped him to make the conversion to Delphi.
This great library which I'm testing with Delphi 2010 is very easy to use and it shows a very interesting example combining different elements and letting them play. You can download the library from here, and test the different modelled items. The results are very well done and with simple steps we can achieve things like this: