Catenary

A black, blue and red exhibit table with an information panel at the back. On the table top are two joysticks and a series of black blocks in the shape of an arch.
A black, blue and red exhibit table with an information panel at the back. On the table top are two joysticks and a series of black blocks in the shape of an arch.

The catenary arch is a strong shape used in buildings and other structures.

How it works

Balance building blocks on an arch-shaped template, then remove the template and test whether the building blocks stay in place or collapse. The shape formed by the building blocks is a catenary arch.

Things to try or ask around the exhibit

When we go home, let's see if we can find the catenary arch shape in natural structures and buildings.

Background

You can make a catenary by hanging a chain or a heavy rope from two points, even if the two points are at different heights. The shape happens because each section of chain is being pulled by the weight of the chain underneath it.

Turning this shape upside down makes an arch, where each bit is pushing straight into the curve underneath. The strength of this curve means you can find catenaries in many different places, from spider webs to powerlines to rope bridges and buildings with arches.