Simulations in social science often ignore the use of any physics engine yet is it can be invaluable for modelling real world situations. Games such as Grand Theft Auto have a built in physics and dymanics simulation to provide variables such as mass, velocity, friction to the in game objects - thus simulating the required environment.
These are often taken for granted, by editing the handling.DAT file in the Grand Theft Auto III directory/data you can change the settings, as the movie above details to interesting effect...
Movie by http://www.youtube.com/user/AnytimeGamers
For more on physics engines see http://en.wikipedia.org/wiki/Physics_engine.
See also the latest post on Physics in the Crysis Engine.