i have lost dropbox public folder and is unable to supply run-able links now.

http://weelookang.blogspot.sg/2014/11/ejss-primary-school-pendulum-energy.html run: Link1, Link2 download: Link1, Link2 source: Link1, Link2 author: Anne Cox, lookang author EJS: Francisco Esquembre |

http://weelookang.blogspot.sg/2014/11/ejss-primary-school-pendulum-energy.html MODEL standalone: https://www.dropbox.com/s/20lc16lg3i2z25a/ejss_model_SHMxvapendulumpri.zip?dl=0 run: https://dl.dropboxusercontent.com/u/44365627/lookangEJSworkspace/export/ejss_model_SHMxvapendulumpri/SHMxvapendulumpri_Simulation.xhtml source: https://www.dropbox.com/s/675lfmdwur52m7p/ejss_src_SHMxvapendulumpri.zip?dl=0 author: lookang, anne cox author of EJSS 5.0 Francisco Esquembre |

## reference:

- http://weelookang.blogspot.sg/2014/02/ejss-pendulum-model.html
- http://academics.eckerd.edu/physics/EJS/Physical_Sci/Energy/ejss_model_pendulum_energy.zip by Anne Cox.

## The equations that model the motion of the pendulum system are:

$ \frac{\delta \theta}{\delta t} = \omega $

$ \frac{\delta \omega}{\delta t} = -\frac{g}{L}( sin \theta) $

where the terms

$ L $ represents the fixed length of the pendulum

$ g $ represents the gravity force component as a result of Earth's pull.

## Energy Equations:

this model uses

$ PE = mg(y-y_{o}) = mgh $

$ PE $ represents potential energy of the mass m

$ y_{o} $ represents the lowest point of the oscillation to facilitate conventions of positive values of PE.

$ y $ represents the vertical height of the mass m

$ KE = \frac{1}{2}mv^{2} $

$ KE $ represents kinetic energy of the mass m

$ v $ represents the velocity of the mass m

$ TE = PE + KE $

$ TE $ represents the total energy of the mass m.