http://www.youtube.com/watch?v=HxTZ446tbzE Tacoma Narrows newsreel *****
http://www.youtube.com/watch?v=bPtlRf6dg8c Simple Harmonic Motion for beginners - in 3 minutes
http://www.youtube.com/watch?v=eeYRkW8V7Vg
animations
http://www.physics.uoguelph.ca/tutorials/shm/Q.shm.html
http://www.phy.ntnu.edu.tw/ntnujava/index.php?topic=148
http://www.surendranath.org/Applets/Oscillations/SHM/SHMApplet.html
stuff
http://hyperphysics.phy-astr.gsu.edu/hbase/shm.html
open source sim Game Maker (by me)
http://rupert.id.au/schoolgamemaker/samples3/mass-spring.gm6
http://rupert.id.au/schoolgamemaker/samples3/mass-spring.exe
Spreadsheet sim
