18 June 2007
Today we'll be having a papercraft automata model of a mechanical paradox that was first presented in 1694 through a published recreational volume called "Pleasure With Profit". You may know it by familiar names such as, the Uphill Roller or Double Cone Incline. In it we have a set of shapes which is comprised of a cylinder, a double cone, and an inclined plane. First we tested the cylinder, and it rolled down the incline, just as gravity would dictate. But when we put the double cone on the bottom of the incline, it seems to defy the rule of gravity and it actually rolls up. This kind of thing might look magical to the untrained, but for those of you who where present in class when this was taught or discussed, then you already know the simple explanation to it.
Ok, I'll try to explain it as easy as can be, this apparent paradox is explained by demonstrating the property of the center of gravity of bodies, which tends naturally to move downward. Since the rails diverge, the center of gravity of the double cone, placed on the axis of rotation at the maximum diameter of the device, does not rise when the entire body seems to move up; on the contrary, the center of gravity descends. For a more detailed and better explanation, with video and trigonometry equations - check this page. And here's the papercraft automata version, from our good friend at paperpino.net
Anti-Gravity Double Cone [Download]
Thanks to Cliffy for creating the short video.