PURPOSE: To demonstrate a center of mass paradox.

DESCRIPTION: When the double cone is placed on the narrow end of the V-shaped rails (at left) and released it rolls to the wide end (at right). The double cone appears to be rolling uphill, but in reality the center of mass is moving down.

SUGGESTIONS: See Question of the Week #62 for information on using this demonstration to enhance class involvement.

REFERENCES: (PIRA 1J11.50) Demonstration B1-06 is a larger version of this demonstration.

EQUIPMENT: Double cone on rails, as photographed.

SETUP TIME: None.