This is a demonstration of a ball rolling down an incline and almost making the loop-the-loop path. The ball does not have enough velocity to make the loop. The velocity required to make the loop is called the critical velocity, and this shows a situation where the ball leaves the surface of the track, or the normal force from the track on the ball is zero. 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 sub 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.