changes made:

1 this is the very first applet that i made, by following the Ejs tutorial since 2007 in yjc days while doing my MAIDT @ NIE. It was not the course that taught me this, but rather it was LEE TL that shared this tool with me during a teabreak or something, that i took it very seriously to explore Ejs. The main driving force was instructional design which was the focus of the masters program, but instructional design with the ability to change learning environment/objects myself is the game changer for me. I never looked back after i found the power of Ejs. This is going to change the physics education world and i am glad to be part of it.
16 june 2010
2 made some checkboxes Force and Energy into menu to save space to fit into width =600 for blog post http://sgeducation.blogspot.com/2010/06/ejs-open-source-simple-harmonic-motion.html
18 March 2011
added a slider to slow down sim for analyze from http://www.phy.ntnu.edu.tw/ntnujava/index.php?topic=2149.0
added text drag mass and release to give hint on the interactivity possible