Tensegrity
While at first this table appears to be defying gravity, it relies on torques and one simple yet important quality of strings to pull off the illusion: strings can only be in tension–not in compression. The top piece, which has a weight vector pointing directly down, is being suspended by a cable at the center, which has a tension vector opposing that of the weight vector. In order for the table to remain still, the forces must remain in equilibrium. If there were only one cable at the center, and the center of mass of the table wasn’t in line with the tension vector, then there would be a net torque on the tabletop causing it to tip over. As a result, taut cables in the corners exert torques that counteract an off-centered weight of the top piece to retain equilibrium. Furthermore, they allow uneven loads on the tabletop, such as the weight of a cup or a book. Placing an object on one side of the table creates a torque through the center cable, about the center of mass of the table. Strings on the opposite side increase their tension while strings on the same side decrease their tension in order to counteract the torque caused by the top loads. Designing this table, I also considered how tension in a string pulls in both directions and inserted dowels into the joints to increase the torque that they could sustain before failing.
Ryan Wong
Description
Essay Title: Tensegrity
Category: Contrived
Photo Number: 6006
School: Temple City High School
Teacher Name: Kevin Slattery