This is an interactive physics calculator that allows you to draw a truss structure (such as a model of a bridge), add supports and loads, and calculate the loads on each member.
Motivation: In Intro to Solid Mechanics class we learned to analyze truss structures by writing force balance equations for each node and solving the system by hand. I wanted a simple tool to do this automatically. At the time (2012), the available online options for this were very cumbersome: they were implemented as clunky Java or Flash applets and required many unnecessary clicks to draw a simple structure. This design is all about hotkeys and click-and-drag interactivity to quickly make and modify designs.