Just click on the green flag and watch the graceful but unpredictable motion of the double pendulum. On page 239 of James Gleick's book Chaos - The Making of a New Science, Peter Richter describes his pet "dynamical system", the double pendulum.
I have made minor changes to Alathea Jensen's original project. If you would like to input the variables see the original project. I have seen several double pendulums made from metal bars and skateboard bearings but they all oscillate through a relatively small number of cycles. For myself, I appreciate the simulated double pendulum because it will run through many many cycles before numerical 'chaos' destroys the simulation. I compliment Alathea Jensen on the ability to code the differential equations given in her credit (see below). I recommend you go to the link and view the derivation of the equations used in the project. For myself, it would have been torturous to code such long lines! I kept her original Credits. Here they are: Numerical simulation of a double pendulum with rainbow trail. Uses Euler's Method to simulate the motion of a double pendulum. Used differential equations found at http://scienceworld.wolfram.com/physics/DoublePendulum.html. Unlike other double pendulum sims done in Scratch, this one is physically accurate. If a double pendulum project doesn't use differential equations, it's not accurate.!
