Demonstrates transformation of potential into kinetic energy. A V-shaped, 12O-cm, metal track in the shape of a loop is fitted on a rectangular wooden base, 42 X 11cm. longer end of the loop stands at an angle to the base and is 50cm high. A steel ball, let loose at upper end of the loop, traversed the track of a fast speed without falling, while climbing the upper track of the top upside down. Instruction included.