High schoolers build geometric structure for math club project

From left, high school students Andrew Dawson (Ithaca), Laura Archer (home school), Marcin Bojanczyk (Dryden), Corey Earle (Dryden), Chris Arsenault (Ithaca) and Peter Speh (Ithaca), members of the Cornell Mathematics Explorers Club, show off the tensegrity they built in Mallott Hall, Dec. 9. Robert Barker/University Photography

By Blaine P. Friedlander Jr.

About 10 high school students from the Ithaca area who are members of Cornell's Mathematics Explorers Club gathered Dec. 9 on campus to demonstrate the power of geometry and build a desk-sized geometric structure -- called a tensegrity -- made of brass tubes, springs and screw eyes.

Robert Connelly, Cornell professor of mathematics and one of the mentors for the club, explains that a tensegrity framework is an ordered, finite collection of points in Euclidean space, called a configuration. Certain pairs of these points, called cables (the springs), are bound in a way that they cannot move farther apart. There are other pairs of these points, called struts (the brass tubes), constrained so that they do not move closer together. The screw eyes (the vertices) provide the turning points for the tensegrity's struts. This can produce a structure of super stability and rigidity, said Connelly.

"The final structure is quite pleasing to look at, I think. It is quite stable and it should last more or less indefinitely," said Connelly. "Actually, there are a lot of methods that have been used by a lot of different people to build tensegrities. There is a kit, called Tensegritoy, that has wooden struts, elastic cables and plastic caps for the vertices. But the club's screw-eyes, springs and brass tubes make this quite novel."