Notice how long the main stick remains horizontal due to the force applied, causing a change in velocity of the main stick. The acceleration is at a minimum at this point. Also take note of the arc the center of mass follows as the stick rotates. In the foil video, there is noticeable slipping when the stick is not hit perfectly perpendicularly. This suggests the presence of friction. (To view these videos, use Microsoft Explorer.)

Burns demonstrating Devil Sticks without aluminum foil.
 

Burns demonstrating Devil Sticks with aluminum foil.
 

Last Updated 1030h.9.6.2002