Bored on a Thursday afternoon? Wish it was friday? getting ready for the weekend a day early?
Then learn about physics and perpetual motion with weights and springs... Brought to you in association with the ICA:
http://www.sodaplay.com/constructor/playerICA.htm
A-level physics not required but helpful ;-)
for more interesting digital art... see www.ICA.org.uk and click online art

PS no gurantees that these models are phyiscally acurate, as I haven't checked how it works yet... but there is a link if you want to satisfy your own curiosity