This is a demonstration of a ball rolling down an incline and making the loop-the-loop path. The velocity required to make the loop is called the critical velocity. The analysis of this demo requires the use of the centripetal force, kinetic energy, potential energy, rolling energy, and friction. This is also an example of a critical velocity. The loop is 19.5 cm in diameter and the ball is 2.5 cm in diameter. The flash illuminates the scene at 40 hz showing images every .025 seconds of time.