APES Practice for Energy Math by Jenny Hoffman is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 3.0 Unported License.
This software incorporates the MathJax TEX and CSS libraries, the JQuery
Google API, and D3.js.
"Collision Detection" interactive is adapted from http://bl.ocks.org/mbostock/3231298 (Copyright (c) 2010-2014, Michael Bostock. All rights reserved).