## EJSS SHM vertical spring mass model for secondary school

based on models and ideas by

 http://weelookang.blogspot.com/2014/08/ejss-shm-vertical-spring-mass-model-for.html EJSS SHM vertical spring mass model for secondary school with equilibrium as y=0 https://dl.dropboxusercontent.com/u/44365627/lookangEJSworkspace/export/ejss_model_SHMxvaverticalsensorsecondary/SHMxvaverticalsensorsecondary_Simulation.xhtml source: https://dl.dropboxusercontent.com/u/44365627/lookangEJSworkspace/export/ejss_src_SHMxvaverticalsensorsecondary.zip author: lookang author of EJSS 5.0 Francisco Esquembre

based on feedback by thong.

1. mass is a circle drawn in pixel to be always the same area drawn
2. mass is $m = \rho \frac{4 \pi r^{3}}{3}$